GENERAL_ASPECTS_OF_ENERGY_MANAGEMENT_AND_ENERGY_AUDIT(CHAPTER 4:ENERGY MANAGEMENT AND AUDIT)

 

GENERAL_ASPECTS_OF_ENERGY_MANAGEMENT_AND_ENERGY_AUDIT

(CHAPTER 4:ENERGY MANAGEMENT AND AUDIT)

Definition and Objectives of Energy Management

The fundamental goal of energy management is to produce goods and provide services with the least cost and least environmental effect. The definition of energy management is:

“The judicious and effective use of energy to maximize profits (minimize costs) and enhance competitive positions” (or)

“The strategy of adjusting and optimizing energy, using systems and procedures so as to reduce energy requirements per unit of output while holding constant or reducing total costs of producing the output from these systems”

The objectives of Energy Management include,

1.To achieve and maintain optimum energy procurement and utilisation, throughout the organization

2.To minimise energy costs / waste without affecting production and quality

3. To minimise environmental effects.

Successful energy management must combine an effective strategy with the right practical action.It begins with the key decision makers, and then involves every employee on a day-to-day basis. Many organisations would like to save energy, but to have the most impact and success, they need to give priority to energy management and make it an integral part of company management strategy.

Energy Audit Definition

Energy Audit is the key to a systematic approach for decision-making in the area of energy management.It attempts to balance the total energy inputs with its use, and serves to identify all the energy streams in a facility. It quantifies energy usage according to its discrete functions. Industrial Energy Audit is fundamental to a comprehensive energy management programme and is defined in EC Act 2001 as follows:

“Energy Audit” means the verification, monitoring and analysis of use of energy including submission of technical report containing recommendations for improving energy efficiency with cost benefit analysis and an action plan to reduce energy consumption.

Need for Energy Audit

In any industry, the three top operating costs are often found to be energy (both electrical and thermal), labour and materials. Among the three, energy has the highest potential for cost reduction. Energy audit will help to understand more about the ways energy is used in the industry, and help in identifying the areas where waste can occur and where scope for improvement exists. Such an audit programme will review variations in energy costs, availability and reliability of supply of energy, decide on appropriate energy mix, identify energy conservation technologies, retrofit for energy conservation equipment etc.

In general, energy audit is the translation of conservation ideas into realities, by evolving technically feasible solutions with economic and other organizational considerations within a specified time.

Types of Energy Audit and Approach

The type of energy audit to be performed depends on the type of industry, the depth to which final audit is needed, and the potential and magnitude of cost reduction desired. Thus energy audit can be classified into the following types: Preliminary Audit, Targeted Energy Audits and Detailed Audit.

Preliminary Energy Audit

Preliminary energy audit, which is also known as Walk-Through Audit and Diagnostic Audit, is a relatively quick exercise and uses existing, or easily obtained data. The scope of preliminary energy audit is to:

¢ Establish energy consumption in the organization (sources: energy bills and invoices)

¢ Obtain related data such as production for relating with energy consumption

¢ Estimate the scope for energy savings

¢ Identify the most likely and the easiest areas for attention (e.g. unnecessary lighting, higher

temperature settings, leakage etc.)

¢ Identify immediate (especially no-/low-cost) improvements/ savings

¢ Set up a baseline or reference point for energy consumption

¢ Identify areas for more detailed study/measurement

Some example of no-cost energy management measures are:

¢ Arresting leaks (steam, compressed air)

* Controlling excess air by adjusting fan damper

Some examples of low-cost energy management measures are:

¢ Shutting equipment when not needed (e.g. idle running of motors)

¢ Replacement with appropriate lamps and luminaires

Areas for detailed study/measurement are:

¢ Converting from direct to indirect steam heated equipment and recovery of condensate

¢ Installing / upgrading insulation on equipment

¢ Modifying process to reduce steam demand

¢ Investigating scheduling of process operations to reduce peak steam or water demands

e Evaluating waste heat streams for potential waste heat recovery

Targeted Energy Audits

Targeted energy audits often results from preliminary audits. They provide data and detailed analysis on specified target projects. For example, an organization may target its lighting system or boiler system or steam system or compressed air system with a view of effecting energy savings. Targeted audits therefore involve detailed surveys of the target subjects and analysis of the energy flows and cost associated with the targets. Final outcome is the recommendations regarding actions to be taken.

Detailed Energy Audit

Detailed energy audit is a comprehensive audit and results in a detailed energy project implementation plan for a facility, since it accounts for the energy use of all major equipment. It considers the interactive effects of various projects and offers the most accurate estimate of energy savings and cost. It includes detailed energy cost saving calculations and project implementation costs.

One of the key elements in a detailed energy audit is the energy balance. This is based on an inventory of energy-using systems, assumptions of current operating conditions, measurements and calculations of energy use.

Detailed energy auditing is carried out in three phases: a) Pre Audit Phase b) Audit Phase and c) Post Audit Phase. A comprehensive ten-step methodology for conducting detailed energy audit is suggested as follows. However, methodology is flexible and can be adapted depending upon the industry concerned.

Ten Steps Methodology for Conducting Detailed Energy Audit

Phase I — Pre Audit Phase
An initial study of the site should always be carried out as proper planning is a pre-requisite for an effective audit. An initial site visit should take only one day and gives the Energy Auditor an opportunity
to meet the personnel concerned, to familiarize with the site and to assess the procedures necessary to carry out the energy audit.
¢ During the initial site visit the Energy Auditor/Engineer should carry out the following actions:
¢ Discuss with the site’s senior management about the aims of the energy audit.
¢ Explain the purpose of the audit and indicate the kind of information needed during the facility tour
¢ Discuss economic guidelines associated with the recommendations of the audit.
¢ Analyze the major energy consumption data with the relevant personnel.
¢ Obtain site drawings where available — plant building layout, steam distribution, compressed air distribution, electricity distribution etc.
¢ Tour the site accompanied by site representative.
The outcome of this visit should be:
¢ To finalise Energy Audit team
¢ To know the expectation of management from the audit
¢ To identify the main energy consuming areas/plant items to be surveyed during the audit.
¢ To identify existing instrumentation and additional metering required prior to audit e.g. for measurement of electricity, steam, oil or gas consumptions 
¢ To plan for audit with time frame
¢ To collect macro data on plant energy resources, major energy consuming equipments
¢ To build up awareness and support for detailed energy audit

Phase II — Detailed Energy Audit Phase
Depending on the nature and complexity of the site, a detailed audit can take from several weeks to several months to complete. Detailed studies would involve investigation and establishment of material and energy balances for specific plant departments or process equipment. Whenever possible, checks of plant operations are carried out over extended periods of time, at night and at weekends as well as during normal daytime working hours, to ensure that nothing is overlooked.

The information to be collected during the detailed audit includes:
1. Sources of energy supplies (e.g. electricity from the grid or self-generation)
2.Energy cost and tariff data
3.Generation and distribution of site services (e.g. compressed air, steam, water, chilled water).
4.Process and material flow diagrams
5.Material balance data (raw materials, intermediate and final products, recycled materials, use of
scrap or waste products, production of by-products for re-use in other industries, etc.)
6.Energy consumption by type of energy, by department, by major process equipment, by end-use
7.Potential for fuel substitution, process modifications, and the use of co-generation system
8.Review of ongoing energy management procedures and energy awareness training programs.

Energy audit team should ensure that the following baseline data are collected:
1. Quantity and type of raw materials
2. Technology, process used and equipment used
3.Capacity utilization
4. Efficiencies / yield
5. Percentage rejection / reprocessing
6. Quantity and types of wastes
7. Consumption of fuel, water, steam, electricity, compressed air, cooling water, chilled water
Energy auditor must specially interview the supervisors and equipment operators as they have information related to the equipment. Maintenance manager is often the primary person to talk about types of lighting, lamps, sizes of motors, A/c plant and electrical load and related performance problems.

Preparing Process Flow Diagram
An overview of unit operations, important process steps, material and energy use and waste generation is then assembled in the form of process flow diagram. Information from existing drawings, records and shop floor survey will help in preparing the flow chart. Simultaneously the team should identify the various inputs and output streams at each process step. A typical example of flowchart of Penicillin-G manufacturing is given in the Figure 4.1.
It may be noted that waste stream (Mycelium) and obvious energy wastes such as condensate drained and steam leakages have been identified in this flow chart. The audit focus will depend upon consumption of input resources, energy efficiency potential, impact of process step on entire process or intensity of waste generation / energy consumption. In case of Penicillin-G manufacturing, the unit operations such as germinator, pre-fermentor, fermentor and extraction are the major energy conservation potential areas identified.

Identification of ENCON Opportunities
Fuel substitution: Identifying the appropriate fuel for efficient energy conversion
Energy Generation: Identifying efficiency opportunities in energy conversion equipment/utility such as feasibility for high efficient DG sets, optimal loading of DG sets, boiler optimization - minimum excess air combustion with boilers / thermic fluid heating, optimising existing efficiencies, efficient energy conversion equipment, biomass gasifiers, Cogeneration etc.
Energy Distribution: Identifying efficiency opportunities in electrical systems such as transformers, cables, switchgears and power factor improvement in electrical systems and chilled water, cooling water, hot water, compressed air, etc.
Energy Usage by Processes: This is where the major opportunity for improvement lies and many of them are hidden. Process analysis is a useful tool for process integration measures.

Technical and Economic Feasibility
The technical feasibility should address the following issues:
¢ Technology availability, space, skilled manpower etc
¢ The impact of energy efficiency measure on safety, quality, production or process.
¢ Reliability, service issues, maintenance requirements and spares availability
The Economic viability often becomes the key parameter for the management acceptance. The economic analysis can be conducted by using Pay back method, Internal Rate of Return method, Net Present Value method etc. For low investment short duration measures, which have attractive economic viability, payback method is sufficient. A sample worksheet for assessing economic feasibility is provided below:
Worksheet for Economic Feasibility
Classification of ENCON Measures
The potential energy saving measures (ENCON) may be classified into three categories:
(a) Low cost — high return
(b) Medium cost — medium return
(c) High cost — high return
Normally the low cost — high return projects receive priority. Other projects have to be analyzed, engineered and budgeted for implementation in a phased manner, Projects relating to equipment and process changes almost always involve high costs coupled with high returns, and required careful scrutiny before funds can be committed. They are complex and need long lead times before they can be implemented. Refer Table 4.1 for project priority guideline.
Energy Audit Report
The length and detail of energy audit report will depend upon the facility audited. The report should begin with an executive summary that provides the management of the audited facility with brief synopsis of the total savings and highlight of each energy saving measure. Executive summary should be tailored to non-technical personnel. The reader who understands the report is more likely to implement the recommended ENCON measures.
The main report should start with general description of the process or facility. Then annual energy consumption and bills should be presented with tables and graphs. This should be followed by description of energy inputs and outputs by major department or by major process and evaluation of efficiency of each step in the process. Then recommended ENCON measures should be presented with calculations for cost and benefits along with expected payback on any capital investment. The audit report should conclude with specific recommendations for detailed engineering studies and feasibility analyses, which must then be performed to justify the implementation of those conservation measures that require high investments. Regardless of the audience for the audit report, it should be written in a clear, concise and easy to understand format and style.

The following worksheets (refer Table 4.2 & Table 4.3) can be used as guidance for energy audit assessment and reporting in Executive Summary. Table 4.4 shows the reporting format for energy conservation recommendations in the main report.
Phase III-Post Audit Phase
On completion of energy audit, energy action plan should be prepared. The energy action plan list the
ENCONSs which should be implemented first, and suggest an overall implementation schedule. Energy audit is incomplete without monitoring and its associated feedback. Monitoring consist of collecting and interpreting data. The data to be collected depends upon goals chosen in the energy action plan. Electrical power consumption and fuel consumption must be evaluated and monitored. The monitoring data should provide direct feedback to those most able to implement the changes. Often additional instruments should be installed in various departments in addition to main metering.

Monitoring should result in more action. Good practices should be replicated. If the gap between planned objectives and actual achievements is large, reasons should be analyzed and new objectives, new actions should be initiated and results should be monitored. In this way, analysis, action and monitoring are a cyclic process.


Understanding Energy Costs
Contrary to common belief, energy costs are not a fixed overhead, there is often a huge potential for making savings. Understanding energy cost is vital factor for awareness creation and saving calculation.
In many industries sufficient meters may not be available to measure all the energy used. In such cases,
invoices for fuels and electricity will be useful. The annual company balance sheet is the other sources
where fuel cost and power are given with production related information.
Energy invoices can be used for the following purposes:
¢ They provide a record of energy purchased in a given year which gives a baseline for future reference
e Energy invoices may indicate the potential for savings when related to production requirements or to air conditioning requirements/space heating etc.
¢ When electricity is purchased on the basis of maximum demand tariff
e They can suggest where savings are most likely to be made.
¢ In later years invoices can be used to quantify the energy and cost savings made through energy conservation measures.

Fuel Costs
A wide variety of fuels are available for thermal energy supply. Some of the fuels are listed below:
¢ Fuel oil
¢ Low Sulphur Heavy Stock (LSHS)
¢ Light Diesel Oil (LDO)
¢ Liquefied Petroleum Gas (LPG)
¢ Coal
¢ Lignite
¢ Wood etc

Understanding fuel cost is fairly simple and it is purchased in Tons or Kiloliters. Availability, cost and quality are the main three factors that should be considered while purchasing. The following factors should be taken into account during procurement of fuels for energy efficiency and economics.
* Price at source, transport charge, type of transport
* Quality of fuel (contaminations, moisture etc)
* Energy content (calorific value)
Power Costs
Electricity price in India not only varies from State to State, but also city to city and consumer to
consumer though it does the same work everywhere. Many factors are involved in deciding final cost
of purchased electricity such as:
¢ Maximum demand charges, kVA
(i.e. How fast the electricity is used?)
¢ Energy Charges, kWh
(i.e. How much electricity is consumed?)
¢ TOD Charges, Peak/Non-peak period
(i.e. When electricity is utilized ?)
¢ Power factor Charge, P.F
(i.e., Real power use versus Apparent power use factor)
¢ Other incentives and penalties applied from time to time
¢ High tension tariff and low tension tariff rate changes
¢ Slab rate cost and its variation
¢ Type of tariff clause and rate for various categories such as commercial, residential, industrial, Government, agricultural, etc.
¢ Tariff rate for developed and underdeveloped area/States
¢ Tax holiday for new projects

Benchmarking
Benchmarking can be a useful tool for understanding energy consumption patterns in an industrial sector and for taking measures to improve energy efficiency. Energy benchmarking for industry is a
process in which the energy performance of an individual plant or an entire sector of similar plants is compared against a common metric that represents ‘standard’ or ‘optimal’ performance. It may also entail comparing the energy performance of a number of plants against each other. Benchmarking forms the basis for monitoring and target setting
Since benchmark tool is used for comparison across a number of plants or sectors, there are two important features they should have. First, because they are applied to plants or sectors of different
sizes and outputs, the metric used should be common irrespective of plant size. The most common
metric used is energy intensity which measures ‘energy use per unit of output’. Second, the tool should
be used in a wide range of facilities so as to compensate for differences in production at similar facilities.

Industrial Benchmarking Programs 
There are three approaches for energy benchmarking. The first approach is to evaluate an entire industrial sector, such as iron and steel, aluminum, cement, etc. This evaluation is used to answer the following questions: How well is this sector performing compared to how it would perform using the best available technologies? How well is it performing compared to the same sector in other countries? Has the sector been improving over time?
The second approach is the comparison of individual plants within a sector. A benchmark-type indicator is calculated for all the facilities within a sector so that they can be compared on even terms. This evaluation can answer the following questions: What is the state-of-the-art performance in this given sector? How does my plant compare against the state-of-the-art? How does it compare against the majority of other plants in the sector? In developing benchmarks at the level of individual plants, the issue of proprietary data becomes important. Individual companies are very reluctant to disclose information about their production processes, particularly if it will be released to their competitors. It is important that the indicators developed are general enough not to reveal any proprietary information and that a credible system is established that encourages plants to trust the process.

The third approach for energy benchmarking that has been seen widely in recent years is for large companies to set themselves energy efficiency goals by using historical best performance as benchmark.
Companies use this approach to set targets for reducing energy use by certain percentages over given time frames. Companies do not need to reveal any proprietary information, since the benchmarking is done internally.
Steps in energy conservation benchmarking are summarized below:
¢ Identify the best available technology for the individual process units.
¢ Collect information to thoroughly understand the process and identify key/controlling parameters.
¢ Determine the performance of the process unit.
¢ Analyse the gap between the existing and the benchmark for the key controlling parameters.
e Set targets or benchmarks, keeping constraints in view, and implement improvements based on the findings
The benchmark parameters for various sectors are given as follows:
¢ Gross Production Related
kWh/MT clinker or cement produced (Cement plant)
kWh/kg yarn produced (Textile unit)
kWh/MT, kcal/kg paper produced (Paper plant)
kcal/kWh Power produced (Heat rate of a power plant)
Million Calories/MT Urea or Ammonia (Fertilizer plant)
kWh/MT of liquid metal output (in a foundry)
Equipment / Utility Related
kWh/ton of refrigeration (on Air-conditioning plant)
% thermal efficiency of a boiler plant
% cooling tower effectiveness in a cooling tower
kWh/Nm; of compressed air generated
kWh/litre in a diesel power generation plant.

While such benchmarks are referred to, related crucial process parameters need to be stated for meaningful comparison among similar industries. For instance, in the above case:
1.For a cement plant — type of cement, blaine number (fineness) i.e. Portland and process used (wet/dry) are to be reported alongside kWh/MT figure.
2.For a textile unit — average count, type of yarn 1.e. polyester/cotton, is to be reported along side kWh/kg figure.
3.For a paper plant — paper type, raw material (recycling extent), GSM quality are some important factors to be reported along with kWh/MT, kcal/kg figures.
4.For a power plant / cogeneration plant — plant % loading, condenser vacuum, inlet cooling water temperature, would be important factors to be mentioned alongside heat rate (kcal/kWh).
5.For a fertilizer plant — capacity utilization(%) and on-stream factor are two inputs worth comparing while mentioning specific energy consumption
6.For a foundry unit — melt output, furnace type, composition (mild steel, high carbon steel/cast iron etc.) raw material mix, number or power trips could be some useful operating parameters to be reported while mentioning specific energy consumption data.
7.For an A/C plant — parity of chilled water temperature level is crucial while comparing kW/TR.
8.For a boiler plant — fuel quality, type, steam pressure, temperature, flow are useful comparators alongside thermal efficiency and more importantly, whether thermal efficiency is on gross calorific  value basis or net calorific value basis or whether the computation is by direct method or indirect heat loss method, mean a lot in benchmarking exercise for meaningful comparison.
9.For a cooling tower - Effectiveness — ambient air wet/dry bulb temperature, relative humidity, air and circulating water flows are required to be reported to make meaningful sense.
10.For a compressed air system - specific power consumption — is to be compared at similar inlet air temperature and pressure of generation.
11.Diesel power plant performance — is to be compared at similar loading %, steady run condition.

Energy Performance
Plant Energy Performance
Plant energy performance (PEP) is the measure of whether a plant is now using more or less energy to manufacture its products than it did in the past: a measure of how well the energy management programme is doing.
Plant energy performance monitoring compares plant energy use of a reference year and the  subsequent years considering production output to determine the improvement (or deterioration) that has been made.
However, since the plants’ production output varies from year to year, it has significant impact on plant’s energy use. For a meaningful comparison it is necessary to determine the energy that would have been required to produce current year’s production output had the plant operated in the same way as it did during the reference year. This calculated value can then be compared with the actual value to determine the improvement or deterioration that has taken place since the reference year.

Production Factor
Production factor is the ratio of production in the current year to that in the reference year.
Production factor is used to determine the energy that would have been required to produce this year’s production output if the plant had operated in the same way as it did in the reference year.

Reference Year Equivalent Energy Use
The reference year's equivalent energy use (or reference year equivalent) is the energy that would
have been used to produce the current year’s production output.
The reference year equivalent is obtained by multiplying the reference year energy use by the production factor (obtained above)
Reference year equivalent = Reference year energy use x Production factor
Plant Energy Performance is the improvement or deterioration from the reference year. It is a measure of plant’s energy progress.
The energy performance is the measure of energy saved at the current rate of use compared to the reference year rate of use. The greater the improvement, the higher the number will be.

Plant energy performance (PEP) is the starting point for evaluating energy performance. It does not require detailed calculations of the energy used by every place of equipment, the energy use of every process or the energy use of buildings. It utilizes the most effective measure of energy savings, the actual measurement of energy consumption compared to production output. Yearly comparisons minimize seasonal effects.
Sometimes, once a plant has started measuring yearly energy performance, management wants more frequent performance information in order to monitor and control energy use on an on-going basis. In such cases PEP can just as easily be used for monthly reporting as yearly reporting.

Matching Energy Usage to Requirement
Mismatch between equipment capacity and user requirement often leads to energy inefficiencies due to part load operations, wastages etc.
The designer always considers safety margins while laying specifications for new equipment leading to oversized equipment. This presents opportunity for energy manager for matching the equipment capacity with user requirement. Some examples for matching energy usage to requirements are listed below:
¢ Eliminating throttling of a pump by impeller trimming, installing variable speed drives and resizing pump
¢ Eliminating damper operations in fans by impeller trimming, installing variable speed drives, pulley diameter modification for belt drives, fan resizing for better efficiency.
¢ Moderating chilled water temperature as per process chilling needs
e Recovering energy lost in control valve pressure drops with back pressure turbine adoption
¢ Adopting of task lighting in place of less effective area lighting

Maximizing System Efficiencies
Once the energy usage and sources are matched properly, the next step is to operate the equipment efficiently through best operation and maintenance practices and adoption of best available technology, if feasible. Some examples are:
¢ Eliminating steam leakages by using appropriate steam traps
e Maximising condensate recovery
¢ Adopting combustion controls for maximizing combustion efficiency
¢ Replacing pumps, fans, air compressors, refrigeration compressors, boilers, furnaces, heaters and other energy conservation equipment, wherever significant energy efficiency margins exist
¢ Ensuring rated electrical parameters at the motor terminals

Optimising Input Energy Requirements
After fine-tuning the energy use practices, attention should be given for minimizing energy input
requirements. The measures include:
¢ Maximising heat recovery from waste energy streams, to minimize purchased energy
¢ Adopting cogeneration plants for balancing heat and power requirements, leading to reduced energy purchases
¢ Adopting cost effective renewable sources of energy such as solar, wind and biomass energy

Fuel and Energy Substitution
Fuel substitution is basically substituting existing fossil fuel with more efficient and less cost/less
polluting fuel such as natural gas, biogas and locally available agro-residues.
Fuel substitution has taken place in all the major sectors of the Indian economy.
Few examples of fuel substitution
e Natural gas is increasingly the fuel of choice as fuel and feedstock in the fertilizer, petrochemicals,
power and sponge iron industries.
¢ Replacement of coal by coconut shells, rice husk etc.
¢ Replacement of LDO by LSHS
There are two ways to reduce energy dependency; energy conservation and substitution.
Few examples of energy substitution
1. Replacement of electric heaters by steam heaters
2.  Replacement of steam based hot water by solar systems

Case Study: Example on Fuel Substitution
A textile process industry replaced old fuel oil fired thermic fluid heater with agro fuel fired heater.
The economics of the project are given below:

Instruments and Metering For Energy Audit
The requirement for an energy audit is to identify and quantify where energy is being used necessitates measurements. These measurements require the use of instruments. The basic instruments used in energy audit work are listed below. These instruments are portable, durable, easy to operate and relatively inexpensive. Key Performance Parameters for Energy Audit
Basic Electrical Parameters in AC & DC systems — Voltage (V), Current (1), Power factor,
Active power (kW), Maximum demand (kVA), Reactive power (kVAr), Energy consumption (kWh),
Frequency (Hz), Harmonics, etc.
Parameters of importance other than electrical such as Temperature and Heat Flow, Radiation , Air
and Gas Flow, Liquid Flow, RPM , Air Velocity, Noise and Vibration, Dust Concentration, TDS, PH,
Moisture Content, Relative Humidity, Flue Gas Analysis — CO2, O2, CO, SOx, NOx, Combustion
Efficiency etc.
Some of the instruments commonly used in an energy audit are described as follows.


Bureau of Energy Efficiency (the manner and intervals of time for conduct of energy audit) Regulations, 2008
Intervals of time for conduct of energy audit
(1) Every designated consumer shall have its first energy audit conducted, by an accredited energy
auditor within 18 months of the notification issued by the Central Government
(2) The interval of time for conduct and completion of subsequent energy audits shall be three
years with effect from the date of submission of the previous energy audit report by the
accredited energy auditor to the management of the designated consumer.
Manner of energy audit
1. Verification of data of energy use
a) Verify the information submitted to the designated agency under the Energy Conservation
(the form and manner for submission of report on the status of energy consumption by the
designated consumers) Rules, 2007 for the previous two years
b) Establish specific energy consumption for the year referred to in clause (a);
c) Disaggregate the energy consumption data and identify major energy using equipment, processes and systems.
2. Scope of energy audit
The accredited energy auditor jointly with the energy manager of the designated consumer shall-
(a) Develop a scope of work for the conduct of energy audit with a view to ensuring adequate coverage in terms of the share of total energy use
(b) Select energy intensive equipment or processes for energy auditing;
(c) Agree on best practice procedures on measuring the energy efficiency performance of selected equipment and on methodology to estimate energy performance and energy savings;
(d) Collect energy consumption, and production data for the equipment and processes covered within the scope of energy audit, operating data, and schedule of operation, non proprietary process flow charts, and production level disaggregated by product, if applicable, and other related historical data essential by the accredited energy auditor for achieving the purpose of energy audit.

3. Monitoring and analysis of the use of energy data for energy audit
The accredited energy auditor shall-
(a) Verify the accuracy of the data collected in consultation with the energy manager as per standard practice to assess the validity of the data collected;
(b) Analyse and process the data with respect to-
(i) Consistency of designated consumers’ data monitoring compared to the collected data;
(ii) Recommendations to reduce energy consumption and improve energy efficiency;
(iii) Summary overview of energy consumption in plant by fuel type and by section;
(c) Conduct equipment energy performance measurements with due diligence and caution.

4.Preparation of recommendations on energy saving measures, their cost benefit analysis
The accredited energy auditor having regard to the overall efficiency of the production process, technoeconomic viability of energy saving measures, site conditions and capacity of the designated consumer to invest for their implementation, shall prepare a list of recommendations to save energy and the list shall include:
(a) A brief description of each recommended measure
(b) The estimated energy saving as well as energy cost reduction potential over a reasonable technical or economic life of the measure;
(c) Any known or expected technical risks associated with each measure;
(d) A preliminary assessment of the financial attractiveness of each measure or assessment of the maximum investment feasible based on the estimated energy cost saving potential over the life of the measure;
(e) Tabulated summary of recommendations listed as per their implementation schedule (short, medium and long term);
(f) Where different alternatives for implementation of an energy efficiency measure are available, the accredited energy auditor shall examine and discuss such options and recommend the techno-financially better option;
(g) Where the installation or implementation of any recommended energy saving measure affects procedures for operation and maintenance, staff deployment and the budget, the recommendation shall include discussion of such impacts including their solutions.

Prioritization and preparation of action plan
(1) The accredited energy auditor jointly with the energy manager shall select from the energy audit report such recommended measures which in the opinion of the designated consumer are technically viable, financially attractive and within its financial means, prioritise them and prepare plan of action for their implementation. This action plan shall include-
(a) Preparation of detailed techno-economic analysis of selected measures;
(b) A monitoring and verification protocol to quantify on annual basis the impact of each measure with respect to energy conservation and cost reduction for reporting to Bureau and the concerned State designated agency;
(c) A time schedule agreed upon by the designated consumer of selected measures taking into consideration constraints such as availability of finance and availability of proposed equipment.
(2) The accredited energy auditor based on the activities undertaken under sub-regulation (4) of regulation 4 and regulation 5 shall submit a report in Form 2 to the management of designated consumer.
(3) The accredited energy auditor shall evaluate the implementation of each recommended energy saving measure in the previous audit report and submit a report in Form 3 to the management of the designated consumer.

Structure of the energy audit report
(1) The energy audit report structure shall be jointly decided by the accredited energy auditor and designated consumer.
(2) The energy audit report shall highlight, details of specific energy consumption, list of recommendations to reduce energy consumption and costs, monitoring and evaluation of impact of selected measures and conclude with certification by accredited energy auditor stating that -
a) The data collection has been carried out diligently and truthfully.a)
b) All data monitoring devices are in good working condition and have been calibrated or certified by approved or authorized agencies and no tempering of such devices have occurred.
c) All reasonable professional skill, care and diligence have been taken in preparing the energy audit report and the contents thereof are a true representation of the facts.
d) Adequate training provided to personnel involved in daily operations after implementation of recommendations.
e) The energy audit has been carried out in accordance with the Bureau of Energy Efficiency (the manner and intervals of time for conduct of energy audit) Regulation, 2008.
3)The accredited energy auditor shall highlight the strengths and weaknesses of the designated consumer in the management of energy and energy resources in the energy audit report and recommend necessary action to improve upon method of reporting data, energy management system in detail along with their underlying rationale, and improving energy efficiency and reducing energy consumption of the designated consumer.
4)The accredited energy auditor shall sign the energy audit report under the seal of its firm giving all the accreditation details along with details of manpower employed in conducting the energy audit.
5) The energy audit report shall include a work schedule sheet duly signed by accredited energy auditor and energy manager of the designated consumer.

Solved Example:
An Energy Manager in a factory has gathered following data to arrive at the Plant Energy Performance.
Reference Year (2009) energy use : 12 million kcal
Production Factor (PF) for the current year (2010) : 0.9
Current year’s energy : 11 million kcal
What is the Plant energy Performance (PEP) of the factory for the year 2010? State your inference.


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Chaptert 5

GENERAL_ASPECTS_OF_ENERGY_MANAGEMENT_AND_ENERGY_AUDIT(CHAPTER 3:BASICS OF ENERGY AND ITS VARIOUS FORMS)

 

GENERAL_ASPECTS_OF_ENERGY_MANAGEMENT_AND_ENERGY_AUDIT

(CHAPTER 3:BASICS OF ENERGY AND ITS VARIOUS FORMS)

Introduction

Energy is described as the ability to do work or as the ability to carry a heat transfer. Energy is required for doing work or involving in a heat transfer. A body is said to possess energy when it has the capacity to do work or the capacity to carry a heat transfer with another body. Work and heat transfer are the transfer of energy from one body to another-so they are called transitory energy. In practical terms energy is what we use to manipulate the world around us, whether by exciting our muscles, by using electricity or by using mechanical devices such as automobiles.

Broadly, energy can be classified as potential (stored) energy and kinetic (working) energy.

Potential Energy

Potential energy is the energy a body possesses because of its position or configuration. For example, driving head of a pile driver has potential energy of position when raised above. On release, driving head comes down to do the piling work. Stretched rubber band or compressed steel spring possesses potential energy of configuration. Both have ability to do work because of their tendency to return to their normal  osition. Potential energy exists in various forms: chemical energy, nuclear energy, stored mechanical energy, gravitational energy etc.

Potential energy stored in a body due to its height above a datum level is expressed by:

Chemical Energy
Chemical energy is the energy stored in the bonds of atoms and molecules and released as heat in a chemical reaction. This is specific to each reaction and is usually given as energy unit mass (e.g. kJ/ kg) or number of molecules (e.g. kJ/mol). Biomass, petroleum, natural gas, propane and coal are examples of stored chemical energy.

Nuclear Energy
Nuclear energy is the energy stored in the nucleus of an atom - the energy that holds the nucleus together. The nucleus of an Uranium atom releases nuclear energy when its’ fission (split in two parts)
results in a loss of mass and the corresponding loss of mass(m) is converted to nuclear energy by
following famous equation of Einstein:

Stored Mechanical Energy
Stored mechanical energy is energy stored in objects by the application of a force. Compressed springs
and stretched rubber bands are examples of stored mechanical energy.

Gravitational Energy
Gravitational energy is the energy of place or position. Water in a reservoir behind a hydropower dam is an example of gravitational energy. When the water is released to spin the turbines, it becomes motion energy in the form of mechanical power-which drives the Generators/Alternators to produce electrical energy.

Kinetic Energy
It is the energy a body possesses by virtue of motion or velocity. For example, a moving vehicle, a flowing fluid and moving parts of machinery all have kinetic energy because of their motion. It exists in various forms: radiant energy, thermal energy, electrical energy, motion energy, sound energy, electrical energy etc.
Radiant Energy
Radiant energy is electromagnetic energy that travels in transverse waves. Radiant energy includes visible light, x-rays, gamma rays and radio waves. Solar energy is an example of radiant energy.

Thermal Energy

Thermal energy is the internal energy in substances - the vibration and movement of atoms and molecules within substances. Geothermal energy is an example of thermal energy.

Motion energy

The movement of objects or substances from one place to another is motion. Wind and hydropower are manifestations of motion energy.

Sound energy

Sound is the movement of energy through substances in longitudinal (compression/rarefaction) waves.

Electrical Energy

Electrical energy is the movement of electrons. Lightning and electricity are examples of electrical energy.

Work, Energy and Power

Work

The unit of work or energy is the joule (J) where one joule is one Newton meter. The joule is defined as the work done or energy transferred when a force of one Newton is exerted through a distance of one meter in the direction of the force. Energy is the capacity for doing work.

Thus, Work done on a body, in Joules W = Fs

Where, Fis the force in Newtons and s is the distance in meters moved by the body in the direction of the force.

In case of rotating body work done is expressed in Joules as:



Energy and Power
Energy represents potential to do work. To actually do the work, one has to use energy of one form at a given rate and convert to another form. Power is defined as the rate of doing work or rate at which energy is used and converted.
The unit of power is Watt (W), where one Watt is one Joule per second.
Thus, power in Watts, P= W/t
Where, W is the work done or energy transferred in Joules and ¢ is the time in seconds.

Example 3.1
A portable machine requires a force of 200 N to move it. How much work is done if the machine is
moved 20 m and what average power is utilized if the movement takes 25 s?
Solution
Work done = force x distance
=200Nx20m
= 4000 Nm or 4 kJ
Power = Work done / time taken = 4000 J /25 s = 160 J/s =160 W

Electricity Basics
Direct Current (DC)
A current which is a non-varying, unidirectional current, e.g. current produced by batteries.

Alternating Current
A current which reverses in regularly recurring intervals of time and which has alternate positive and negative values occurring specified number of times., e.g. current from utilities. In 50 Cycle (Hertz) AC, current reverses direction 100 times per second i.e. two times in one cycle.

Amps or Ampere (A)
Current is the rate of flow of charge. Ampere is the basic unit of electric current.

Voltage or Volts (V)
It is a measure of electric potential or electromotive force. A potential of one Volt (V) appears across a
resistance of one Ohm when a current of one Ampere flows through the resistance. In case of Alternating Current (AC) —the Voltage or Current value normally mentioned is Root Mean Squared (RMS) value so that we can use the same formula for calculating power just like a Direct Current (DC) application.

Resistance and Conductance
The unit of electric resistance is the ohm () where one ohm is one volt per ampere. It is defined as the resistance between two points in a conductor when a constant electric potential of one volt applied at the two points produces a current flow of one ampere in the conductor. Thus, resistance, in ohms
R = Volts /Amp = V/I
where V is the potential difference across the two points in volts and / is the current flowing between the two points in amperes.
The reciprocal of resistance is called conductance and 1s measured in siemens (S). Thus, conductance,
in mho or Siemens G = //R, where R is the resistance in ohms.

Frequency (Hertz)
The supply frequency is the number of cycles at which alternating current changes. The unit of frequency is cycles / second or Hz. In India-the normal supply frequency by utilities is at 50 Hz.

Electrical Energy
When a direct current (DC) of J amperes is flowing in an electric circuit and the voltage across the circuit is V volts, then,
Power, in Watts P= VI
Electrical energy = Power x time
= V x I x t Joules
The same formulae can be used in AC applications as well (since voltage and current are normally
expressed in RMS values for AC applications)
Although the unit of energy is the Joule, when dealing with large amounts of energy, the unit used is
the kilowatt hour (kWh ) where
1 kWh = 1000 Watt hour
= 1000 x 3600 Watt seconds or Joules
= 3,600,000 J

Example 3.2
An electric heater consumes 1.8 MJ when connected to a 250 V supply for 30 minutes. Find the power
rating of the heater and the current taken from the supply?
Solution
Energy = power x time,
Power = Energy / time
Hence, the current taken from the supply is 4 A.

Example 3.3
A 100 W electric light bulb is connected to a 250 V supply. Determine (a) the current flowing in the
bulb, and (b) the resistance of the bulb
Solution
Power P = V x I from which, current I = P/V
(a) Current, I = 100/250 =0.4 A

Power Factor
The total power requirement is comprised of two components, as illustrated in the power triangle,
Figure 4-1. This diagram shows the resistive portion or kilowatt (kW), 90° out of phase with the reactive portion, kilovolt ampere reactive (kvar). The reactive current is necessary to build up the flux for the magnetic field of inductive devices, but otherwise it is non-usable. The resistive portion is also known as the active power which is directly converted to useful work. The hypotenuse of the power triangle is referred to as the kilovolt ampere or apparent power (kVA). The angle between kW and kVa is the power factor angle.
Which applications use single-phase power in an industry?
Single-phase power is mostly used for lighting, fractional HP motors and electric heater applications.

Example 3.7
A 400 Watt mercury vapor lamp was switched on for 10 hours per day. The supply volt is 230 V. Find
the energy consumption per day? (Volt = 230 V, Current = 2 amps, PF = 0.8)

Motor Loads
Each electrical load in a system has an inherent power factor. Motor loads are usually specified by
horsepower ratings. These may be converted to kVA, by use of Equation.
Most motor manufacturers can supply information on motor efficiencies and power factors. Smaller
motors running partly loaded are the least efficient and have the lowest power factor.

Example 3.8
A 3-phase AC induction motor (20 kW capacity) is used for pumping operation. Electrical parameters
such as current, volt and power factor were measured with power analyzer. Find the energy consumption of motor in one hour? (Volts. = 440 V, current = 25 amps and PF = 0.90).
Motor loading calculation
The name plate details of motor, KW or HP indicates the output of the motor at full load The other parameters such as volt, amps , PF are the input condition of motor at full load.

Example 3.9
A 3-phase 10 kW motor has the name plate details as 415 V, 18.2 amps and 0.9 PF. Actual input measurement shows 415 V, 12 A and 0.7 PF which was measured with power analyzer during motor running. Find out the motor loading and actual input power of the motor.
Solution
Rated output at full load =10KW
Rated input at full load = 1.732x0.415x18.2x0.9 = 11.8 kW
The rated efficiency of motor = 10/11.8 = 85%
Measured (Actual) input power = 1.732x 0.415 x 12x 0.7 = 6.0 kW
Thermal Energy Basics
Temperature
Temperature is a physical property that quantitatively expresses the common notions of hot and cold.
Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot.
Temperature is measured with thermometers, which may be calibrated to a variety of temperature scales. Much of the world uses the Celsius scale for most temperature measurements. In Fahrenheit scale (British system), the freezing point of water is 32°F and the boiling point of water is 212°F at
atmospheric pressure.
The Kelvin scale is the temperature standard for scientific or engineering purposes. It has the same incremental scaling(1°) as the Celsius scale, but fixes its origin, or null point, at absolute zero (°K =
—273.15°C)
Conversion of the degree Celsius into Fahrenheit = (degrees C x 1.8) + 32
Conversion of the Fahrenheit into degree Celsius = (degrees F - 32) / 1.8
Degrees Celsius (C) to degrees Kelvin (KK) = (C) + 273 = (KK)

Pressure
It is the force per unit area applied to outside of a body.
P= F/A= ma/A = mg/A (when g=a)
Where,
P is the pressure in N/m2 or Pascals
F is the force in Newtons (N)
a is the acceleration in m/s2
g is the acceleration due to gravity in m/s2

Absolute pressure
The absolute pressure (ps) is total or true pressure. It is measured relative to the absolute zero pressure
- the pressure that would occur at absolute vacuum. All calculation involving the gas laws requires pressure to be in absolute units and temperature in Kelvin.

Gauge Pressure
Gauge pressure (pg) is the pressure indicated by a gauge. All gauges are calibrated to read zero at atmospheric pressure. Gauges indicated the pressure difference between a system and the surrounding
atmosphere. The gauge pressure can be expressed as
Atmospheric Pressure
Atmospheric pressure (pa) is pressure in the surrounding air at the surface of the earth. The atmospheric pressure varies with temperature and altitude above sea level.

Standard Atmospheric Pressure
Standard Atmospheric Pressure (atm) is used as a reference for gas densities and volumes. The Standard Atmospheric Pressure is defined at sea-level at 273°K (0°C) and is 1.01325 bar or 101325
Pascal (absolute). The temperature of 293°K (20°C) is also used.

Heat
Heat is transferred from one body to another body at a lower temperature by virtue of temperature difference i.e. Heat is energy in transition or transitory energy. The quantity of heat depends on the quantity and type of substance involved.

Calorie is the unit for measuring the quantity of heat. It is the quantity of heat, which can raise the
temperature of 1 g of water by 1°C.
Calorie is too small a unit for many purposes. Therefore, a bigger unit Kilocalorie (1 Kilocalorie =
1000 calories) is used to measure heat. | kilocalorie can raise the temperature of 1000g (i.e. 1kg) of
water by 1°C.
However, nowadays generally Joule as the unit of heat energy is used. It is the internationally accepted
unit. Its relationship with calorie is as follows:
1 Calorie = 4.187 J
24.2 J

Specific Heat
If the same amount of heat energy is supplied to equal quantities of water and milk, their temperature goes up by different amounts. This is due to different specific heats of different substances. Specific heat is defined as the quantity of heat required to raise the temperature of 1kg of a substance through 1°C or 1 K. Specific heat is expressed in terms of kcal/kg°C or J/kg K. Specific heat varies with temperature. In case of gases-there are an infinite number of processes in which heat may be added to raise gas temperature by a fixed amount and hence a gas could have an infinite numbers of specific heat capacities. However-only two specific heats are defined for gases i.e. specific heat at constant pressure, c, and specific heat at constant volume ,c.. For solids and liquids, however, the specific heat does not depend on the process. The specific heat of water is very high as compared to other common substances; it takes a lot of heat to raise the temperature of water. Also, when water is cooled, it gives out a large quantity of heat. The specific heats of common substances are given in Table 3.1.

Sensible Heat
The amount of heat which when added to any substance causes a change in temperature. The changes
in temperature that do not alter the moisture content of air. It is expressed in calories or Joules.
Sensible heat = mass x specific heat x change in temperature

Phase Change
The change of state from the solid state to a liquid state is called fusion. The fixed temperature at which a solid changes into a liquid is called its melting point. The change of a state from a liquid state to a gaseous is called vaporization. The fixed temperature at which a liquid changes into a vapour is called its boiling point. The change of a state from gaseous state to a liquid state is called condensation.

Latent heat
It is the change in heat content of a substance, when its physical state is changed without a change in
temperature.

Latent heat of fusion
The latent heat of fusion of a substance is the quantity of heat required to convert | kg solid into liquid state without change of temperature. It is represented by the symbol hif. Its unit is Joule per kilogram (J/Kg) Thus, Q, (ice) = 335 KJ/kg. The change in phase occurs in either direction at the fusion temperature i.e. liquid to solid and solid to liquid. The temperature and quantity of heat to bring about the change will be the same in either case and can be determined from the following equation:
Example 3.10
If the latent heat of fusion of water is 335 kJ/kg, determine the quantity of latent heat given up by 10
kg of water at 0°C when it freezes into ice at 0°C.
QL = 10 kg x 335 kJ/kg = 3350 kJ

Example 3.11
If 20 kJ of heat is supplied to 25 kg of ice at 0°C, how many kilograms of ice will be melted into water?
m=QL /hIF.=20 kJ/335 kJ/kg = 0.06 kg

Latent Heat of Vaporization
The quantity of heat that a 1 kg mass of liquid will absorb in going from the liquid phase to the vapour
phase, or give up in going from the vapour phase to the liquid phase, without change in temperature,
is called latent heat of vaporization.
It is also denoted by the symbol Q, and its unit is J/kg. The latent heat of vaporization of water is 2257
KJ/kg. When 1 kg of water at 100°C vaporizes to form steam at 100°C, it absorbs 2257 kcal/kg (540
kcal/kg) of heat.

Where,
Q, = The quantity of latent heat in kilojoules
m = The mass in kg
hfg= The latent heat of vaporization in kJ/kg

Condensation
Condensation is the change by which any substance is converted from a gaseous state to liquid state without change in temperature. When | kg of steam at 100 condenses to form water at 100°C, it gives out 2260 kJ of heat.

Example 3.12
Determine the quantity of heat required to vaporize 2 m3 of water at 100°C if the latent heat of vaporization of water at that temperature is 2257 kJ/kg
QL = 2000 kg x 2257 kJ/kg = 4514000 kJ

Super Heat
Super heating is the heating of vapour, particularly saturated steam to a temperature much higher than the boiling point (also called saturation temperature) at the existing pressure. This is done in power plants to improve efficiency and to avoid condensation in the turbine. Here it is noteworthy to mention that higher the pressure of water-higher the saturation temperature at corresponding pressure. This property of water can be depicted by the following Temperature- entropy(T-S) diagram:

Entropy in horizontal axis is commonly understood as a measure of disorder of a substance.
The area under the dome is the binary phase 1.e. water and steam mixture. The blue lines are constant pressure line and these lines under the dome represent the latent heat region (i.e. constant temperature and pressure heating resulting into phase change from water to steam).
X=dryness factor of steam=in 1 kg of water-steam mixture, x kg is mass of steam and (1-x) kg is mass of water.
Thus the zone in right side of X=1.0 line represents the superheated region of steam.

Humidity
Moisture contained in air is expressed as Humidity. Saturated air holds all the moisture it can at that temperature and pressure.
The unit for humidity is kg of moisture / kg of dry air.

Dew Point
It is the temperature at which water vapor in the air becomes saturated with moisture and the moisture starts to condense into water droplets. It is equal to the saturation temperature at the partial pressure of the water vapour in the mixture.

Specific Humidity or Humidity Ratio
It is the mass (kg) of the water vapor in each kg of dry air (kg/kg).

Relative Humidity (RH)
It is the ratio of mass of water vapour actually held by the air in a given volume to that which air could hold at the same temperature if the air were saturated. It is expressed as a percentage. Warmer air will hold more water vapour and saturated air cannot hold any more water vapour.
Relative humidity affects comfort conditions. An air sample that is at 50% RH is holding half the moisture it is capable of holding at the same temperature (at dew point or saturated).

Dry bulb and Wet bulb Temperatures
Dry bulb measures sensible heat content in air-vapour mixtures. Dry bulb temperature is not influenced by RH. It is the temperature recorded by the thermometer with a dry bulb.

Wet bulb thermometer has wick saturated with distilled water enveloping the bulb of the thermometer. The evaporation of water lowers temperature, taking the latent heat from the water-soaked wick-thus decreasing the temperature recorded. Wet bulb temperature takes into account RH.
If relative humidity is 100%, dew point, wet bulb and dry bulb temperatures are all the same.

Enthalpy of air
It is the measure of total heat content of air and water vapor mixture measured from pre-determined base point. It is expressed as kcal/kg or Joules/kg. Enthalpy of air stream can be determined by measuring dry and wet bulb temperature and referring the psychometric chart.

Fuel Density
Density is the ratio of the mass of the fuel to the volume of the fuel at a stated temperature. Density
is expressed in kg/m3.

Specific gravity of fuel
The specific gravity of fuel is the ratio of density of fuel to that of water. The specific gravity of water is defined as 1. As it is a ratio there are no units. Higher the specific gravity, higher will be the heating values. Specific gravity has no dimensions.

Viscosity
The viscosity of a fluid is a measure of its internal resistance to flow. All liquid fuels decrease in viscosity with increasing temperature.
Viscosity is measured in Stokes / Centistokes. Sometimes viscosity is quoted in Engler, Saybolt or Redwood.

Energy Content in Fuel
Energy content (Calorific Value) in an organic matter can be measured by burning it and measuring the heat released. This is done by placing a sample of known mass in a bomb calorimeter, a device that is completely sealed and insulated to prevent heat loss. A thermometer is placed inside (but it can be read from the outside) and the increase in temperature after the sample is burnt completely is measured. From this data, energy content in the organic matter can be found out.
The heating value of fuel is the measure of the heat released during the complete combustion of unit weight of fuel. It is expressed as Gross Calorific Value (GCV) or Net Calorific Value (NCV). The difference between GCV and NCV is the heat of vaporization of the moisture and atomic hydrogen (conversion to water vapour) in the fuel. Typical GCV and NCV for heavy fuel oil are 44100 J/kg (10,500 kcal/kg) and 41160 J/kg (9,800 kcal/kg).

Heat transfer
Heat will always be transferred from hot to cold independent of the mode. The energy transferred is measured in Joules. The rate of energy transfer, more commonly called heat transfer, is measured in Watts (J/s)

Heat is transferred by three primary modes:
¢ Conduction (Energy transfer in a solid)
¢ Convection (Energy transfer in a fluid)
¢ Radiation (doesn’t need a material to travel through)
Conduction is the primary mode of heat transfer through solid. Conduction occurs by two
mechanisms
1. Molecular Motion. Molecules of higher energy (motion) impart that energy to adjacent molecules of lesser energy.
2.Migration of free electrons. This is primarily associated with pure metals

Convection occurs when a fluid exchanges energy with an adjacent solid. The fluid motion adjacent to the solid surface assists in the transfer of energy

There are two types of convection heat transfer:
1. Forced convection - Fluid motion is induced by an external source such as a fan or pump
2. Natural convection - Heating a fluid results in natural convection heating. Air will circulate
due to natural convective heating. The temperature gradient in the fluid creates variations in density within the fluid. The colder fluid (heavier) will sink, and the hotter fluid (lighter) will rise.

Radiation mode heat transfer requires no medium for the transport of heat. Energy can be radiated from a body over a wide range of wavelengths. Thermal radiation is only a small portion of the electromagnetic spectrum shown and it encompasses infrared light to ultraviolet light. Radiant energy that strikes a surface can be reflected, absorbed and transmitted.

Steam Properties
Evaporation
When a liquid evaporates it goes through a process where
1. The liquid heats up to the evaporation temperature
2.The liquid evaporate at the evaporation temperature by changing state from fluid to gas
3.The vapor heats above the evaporation temperature - superheating
The heat transferred to a substance when temperature changes is often referred to as sensible heat. The heat required for changing state as evaporation is referred to as latent heat of evaporation.
The most common vapor is evaporated water - steam.

Enthalpy of steam
Enthalpy of a system is defined as the mass of the system - m - multiplied by the specific enthalpy
- h - of the system and can be expressed as:
H=mh
Where,
H = enthalpy (kJ)
m = mass (kg)
h = specific enthalpy (kJ/kg)

Specific Enthalpy
Specific enthalpy is a property of the fluid and can be expressed as:
h=u+pv
Where,
u = internal energy (kJ/kg)
p = absolute pressure (N/m2)
v = specific volume (m3/kg)
Part of the water vapor - steam - properties can be expressed in a table as:

Specific Enthalpy of Saturated Water
Specific enthalpy of saturated water - hf - can be obtained from tables as above. The value depends on
the pressure.
For saturated water at standard atmosphere -the specific enthalpy - h, - is 419 kJ/kg. At standard atmosphere - / bar (14.7 psi) - water starts boiling at 100 °C (212 °F). The specific enthalpy of water (in SI units) can be calculated from:

Specific Enthalpy of Saturated Steam
Specific enthalpy of saturated steam - hg - can be obtained from tables as above. The value depends on the pressure.
For saturated steam at standard atmosphere - the specific enthalpy - hg - 18 2676 kJ/kg. The specific enthalpy of evaporation can be calculated from:

Where,
he = specific evaporation enthalpy (kJ/kg)
Specific evaporation enthalpy for water at standard atmosphere is:
he = (2676 kJ/kg) - (419 kI/kg)
= 2257 (kJ/kg)

Specific Enthalpy of Superheated Steam
The specific enthalpy of superheated steam can be calculated from:
The laws of thermodynamics
Thermodynamics is the study of heat and work, and the conversion of energy from one form into another. There are actually three laws of thermodynamics, although the majority of thermodynamics is based on the first two laws.

The first law of thermodynamics
The first law of thermodynamics is also known as the law of conservation of energy. It states that the energy in a system can neither be created nor destroyed. Instead, energy is either converted from one form to another, or transferred from one system to another. The term ‘system’ can refer to anything from a simple object to a complex machine. If the first law is applied to a heat engine, such as a gas turbine, where heat energy is converted into mechanical energy, then it tells us that no matter what the various stages in the process, the total amount of energy in the system must always remain constant.

The second law of thermodynamics
While the first law of thermodynamics refers to the quantity of energy that is in a system, it says nothing about the direction in which it flows. It is the second law which deals with the natural direction of energy processes. For example, according to the second law of thermodynamics, heat will always flow only from a hot object to a colder object.
Another term arising from the second law of thermodynamics is the term ‘entropy’ which means  disorder. Entropy can be used to quantify the amount of useful work that can be performed in a system.
In simple terms, the more chaotic or disorderly a system, the more difficult it is to perform useful work.
It is the second law of thermodynamics that accounts for the fact that a heat engine can never be 100%
efficient. Some of the heat energy from its fuel will be rejected to the surroundings, with the result that
it will not be converted into mechanical energy.

The third law of thermodynamics
The third law of thermodynamics is concerned with absolute zero (i.e. -273 °C). It simply states that it is impossible to reduce the temperature of any system to absolute zero.

Energy Units and Conversions
SI system has 6 base units on which other units are derived. The base units are:
The examples of derived units from base units are:
SI derived units are given special names and symbols for better understanding. Some derived SI units
relevant to Energy Management & Audit are listed below:


Temperature Units
Conversion of the degree Celsius into Fahrenheit = degrees C x 1.8 + 32
Conversion of the Fahrenheit into degree Celsius = (degrees F - 32.) / 1.8
Degrees Celsius (C) to degrees Kelvin (K) = (C) + 273.15 = (K)

Pressure Units

Energy Units and Conversions
Energy Conversion values used for working out annual energy consumption in terms of metric
tone of oil equivalent (as per Gazette of India Part II Sec 3 Sub-sec(ii) 19-03-2007)
1 kWh - 860 kilocalories (kcal)
1 kg. Coal/Coke - Gross Calorific Value as per supplier’s (coal company's) latest certificate
1 kg. Charcoal - 6,900 kcal or as per supplier's latest certificate
1 kg. Furnace Oil/RFO/LSHS/NAPTHA - 10,050 kcal (density = 0.9337 kg/litre) or as per
supplier’s latest certificate
1 kg. HSD - 11,840 kcal (density = 0.8263 kg/litre) or as per supplier’s latest certificate
1 kg. Petrol - 11,200 kcal (density = 0.7087 kg/litre) or as per supplier’s latest certificate
1 kg. Kerosene - 11,110 kcal (density of SKO = 0.7782 kg/litre) or as per supplier’s latest
certificate.
1 kg. LPG - 12,500 kcal or as per supplier's latest certificate
1 m? Natural Gas - 8,000-10,500 kcal (Actual calorific value as per supplier’s latest certificate
may be considered. In case of non-issue of certificate by the supplier, average of the range 8000
-10,500 kcal/m? may be considered).

For the purpose of this table
Y 1kg of Oil Equivalent: 10,000 kcal
Y 1 Metric Tonne of Oil Equivalent (MTOE) : 1 x 10’ kcal
v Incase of coal, petroleum products and other fuels in absence of supplier certificate, GCV of the
above fuel (fuel sample) will be considered as per the test Certificate from a NABL Accredited
Lab or State Government Lab or Gov. recognized Lab

For different type of fuel these following formulas can be used for MTOE conversion:
1. For solid fuel,
(Quantity of solid fuel used in kg X GCV of fuel used in kcal/kg)/10^7
For Liquid fuel,
(Quantity of liquid fuel used in kg or liters X GCV of fuel used in kcal/kg or liters)/10^7
For gaseous fuel,
(Quantity of gaseous fuel used in kg or Nm? X GCV of fuel used in kcal/kg or Nm})/10^7

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