Unit 61 Engineering Thermodynamics



Unit 61:

Engineering Thermodynamics


Unit code:
D/601/1410

QCF level:
5


Credit value:
15






Aim

This unit will extend learners’ knowledge of heat and work transfer. It will develop learners’ understanding of the principles and laws of thermodynamics and their application to engineering thermodynamic systems.

Unit abstract

This unit will build on learners’ understanding of polytropic expansion/compression processes, the first law of thermodynamics and the concepts of closed and open thermodynamic systems. Learners are then introduced to the second law of thermodynamics and its application in the measurement and evaluation of internal combustion engine performance. This is followed by measurement and evaluation of air compressor performance. Finally, learners will develop an understanding of the layout and operation of steam and gas turbine power plants.

Learning outcomes

On successful completion of this unit a learner will:

1     Understand the parameters and characteristics of thermodynamic systems

2     Be able to evaluate the performance of internal combustion engines

3     Be able to evaluate the performance of reciprocating air compressors

4       Understand the operation of steam and gas turbine power plant.


Unit content

1      Understand the parameters and characteristics of thermodynamic systems

Polytropic processes: general equation pvn = c, relationships between index ‘n’ and heat transfer during a process; constant pressure and reversible isothermal and adiabatic processes; expressions for work flow

Thermodynamic systems and their properties: closed systems; open systems; application of first law to derive system energy equations; properties; intensive; extensive; two-property rule

Relationships: R = cp cv and γ = cp/cv


2      Be able to evaluate the performance of internal combustion engines

Second law of thermodynamics: statement of law; schematic representation of a heat engine to show heat and work flow

Heat engine cycles: Carnot cycle; Otto cycle; Diesel cycle; dual combustion cycle; Joule cycle; property diagrams; Carnot efficiency; air-standard efficiency

Performance characteristics: engine trials; indicated and brake mean effective pressure; indicated and brake power; indicated and brake thermal efficiency; mechanical efficiency; relative efficiency; specific fuel consumption; heat balance

Improvements: turbocharging; turbocharging and intercooling; cooling system and exhaust gas heat recovery systems

3      Be able to evaluate the performance of reciprocating air compressors

Property diagrams: theoretical pressure-volume diagrams for single and multi-stage compressors; actual indicator diagrams; actual, isothermal and adiabatic compression curves; induction and delivery lines; effects of clearance volume

Performance characteristics: free air delivery; volumetric efficiency; actual and isothermal work done per cycle; isothermal efficiency

First law of thermodynamics: input power; air power; heat transfer to intercooler and aftercooler; energy balance

Faults and hazards: effects of water in compressed air; causes of compressor fires and explosions


4      Understand the operation of steam and gas turbine power plant

Principles of operation: impulse and reaction turbines; condensing; pass-out and back pressure steam turbines; single and double shaft gas turbines; regeneration and re-heat in gas turbines; combined heat and power plants

Circuit and property diagrams: circuit diagrams to show boiler/heat exchanger; superheater; turbine; condenser; condenser cooling water circuit; hot well; economiser/feedwater heater; condensate extraction and boiler feed pumps; temperature-entropy diagram of Rankine cycle

Performance characteristics: Carnot, Rankine and actual cycle efficiencies; turbine isentropic efficiency; power output; use of property tables and enthalpy-entropy diagram for steam
Learning outcomes and assessment criteria


Learning outcomes
Assessment criteria for pass


On successful completion of
The learner can:


this unit a learner will:










LO1 Understand the parameters

1.1
evaluate polytropic process parameters


and characteristics of

1.2
explain the operation thermodynamic systems and


thermodynamic systems





their properties









1.3
apply the first law of thermodynamics to





thermodynamic systems




1.4
determine the relationships between system





constants for an ideal gas








LO2 Be able to evaluate the

2.1
apply the second law of thermodynamics to the


performance of internal


operation of heat engines


combustion engines

2.2
evaluate theoretical heat engine cycles








2.3
evaluate the performance characteristics of spark





ignition and compression ignition internal





combustion engines




2.4
discuss methods used to improve the efficiency of





internal combustion engines







LO3 Be able to evaluate the

3.1
evaluate property diagrams for compressor cycles


performance of reciprocating

3.2
determine the performance characteristics of


air compressors





compressors









3.3
apply the first law of thermodynamics to





compressors




3.4
identify compressor faults and hazards







LO4 Understand the operation of

4.1
explain the principles of operation of steam and gas


steam and gas turbine power


turbines


plant

4.2
illustrate the functioning of steam power plant by









means of circuit and property diagrams




4.3
determine the performance characteristics of steam





power plant.









Guidance

Links

This unit has links with Unit 1: Analytical Methods for Engineers, Unit 2: Engineering Science and Unit 41: Fluid Mechanics.

Essential requirements

Laboratory facilities will need to be available for the investigation of the properties of working fluids, internal combustion engines and compressor performance.

Employer engagement and vocational contexts

Liaison with industry can help centres provide access to relevant industrial laboratory facilities, engines, compressors and related plant.

Where possible, work-based experience should be used to provide practical examples of the characteristics of thermodynamic systems.

A visit to a power station will be of value to support delivery of learning outcome 4.

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