Question

You are a Project Engineer in a well-known engineering consulting company. One of your
clients, Dato’ Ang Chun Kit is very keen to sponsor a group of UCSI students to represent
Malaysia in an Innovative Gas Power Cycle Competition, to be held in Japan. The main
objectives are to build a prototype which operates at promisingly high and stable
efficiencies, but at the same time can be economically and/or environmentally attractive.
In your first meeting with Dato’ Ang, you have presented the conceptual ideas of the
prototype to be operated on cycles below:
▪ Stirling Cycle
▪ Ericsson Cycle
▪ Brayton Cycle
By analysing all three cycles above in terms of working principles, advantages, and
disadvantages, identify the most suitable cycle for Dato’ Ang’s sponsorship. With
reasonable arguments, justify why the prototype operated on that cycle is proposed, and
how the cycle can fulfil all the objectives.

Answer 1

(1) stirling cycle Odoorking forinciple 9+ is a closed cycle that consists of four thermo- dynamic process on the cycle (1) gs Othermal expansion (11) constant volume Isothermal compression av isochoric Bocess takes Phace or isochoric Process V casists of fixed most of a gas est commonly atte Hydrogen er retium. emission. a lot Advantages - c) Stirling cooling system operates with very low noise (1) Absorption type refrigerator use of energy () Hydrogen is the working fluid which is enviromental friendly (v) with refer regenerator cop approaches carnot Cop (V) component used in stirling refrigeration be easily reusable and reculable. can

e Disadvantages o gt is this cycle cost of engine is High. engine complex (11) The Ericsson cycle and two gt consists of two is othermal Constant pressure Process 3 P V → Process - 1-2 ; at a → Process 2-3 : The during this constant temperature the Pressure of air is increased therefore the compression takes place. increased Pressure Process is maintained to & further heat is added to the cylinder, Now the temperature again maintained constant and increases there fore expansion takes Place is Process 3-4 » the volume of air the Pressure maintaining process 4-1 ; Again constant , neat is removed from the cylinder system Hence process reachel lits initial state make the process reversible, to

Advantages + - ) High Power (1) low emission (11) variety of fuels Dis advantage (i) High cost ² Brayton cycle gt 18 a thermodynamic cycle that described the working of constant pressure heat engine The original Brayton og engine used a pis ton compressor and piston expande But more modern gas turbine engine & a is breathing jet engines also follow. Although the cycle is usually op en system it it is conventionally for the purposes of the modynamies that exhaust reused en en-abling analysis as closed system, run as an assumed gases are analysis the intake P s = const S = coms 4 taw a out 1-2 > V adiabatic process (compression) Heat addition adiabat process (expansions isobaric process Heat rejection 3-4 > 4-17

Advantages & (1) High Power weight ratio (11) compact (11) one direction motion -vibration fewer moving parts ) variety of of fuels Low emissions Disadvantages - Higher (1) cost not enviomment friendly huke the most so, above three After analysis stirling 13 suitable cycle Because (11) silent environmental Harmless High theoretical efficiency Operation, (V) 9t is closed cyclic system (V) The fuel the combustion air and the products of combustion donot enter the engine cylinder become working gas.