1. ME 200 L38 CARNOT REFRIGERATION CYCLE Read 10.1 Material not picked up this week may be recycled! ME 200 L38 CARNOT REFRIGERATION CYCLE Read 10.1 Kim Sees Office ME Gatewood Wing Room 2172 Examination and Quiz grades are available Blackboard Examinations and Quizzes can be picked up all of this week from Gatewood Room 2172 Material not picked up this week may be recycled! https://engineering.purdue.edu/ME200/ ThermoMentor © Program Spring 2014 MWF 1030-1120 AM J. P. Gore gore@purdue.edu Gatewood Wing 3166, 765 494 0061 Office Hours: MWF 1130-1230 TAs: Robert Kapaku rkapaku@purdue.edu Dong Han han193@purdue.edurkapaku@purdue.eduhan193@purdue.edu

2. Features of Carnot Refrigeraiton Cycle Heat transfers between refrigerant and cold and warm regions are not reversible. Refrigerant temperature in evaporator is less than T C. Refrigerant temperature in condenser is greater than T H. Irreversible heat transfers have negative effect on performance. 2 sCarnot 3 Carnot 1 Carnot 4 Carnot 3 High-COP-Carnot 2 High-COP-Carnot 1 High-COP-Carnot

3. Carnot Refrigeration Cycle Compressor for a mixture is challenging to engineer Condenser with pressure gain is challenging. Expansion valve replaced by turbine generates only a small amount of work. Condenser input state is identical between the option cycles and may have mixture exit or saturated vapor exit. Hard to achieve refrigeration cycle but still the goal. Two-phase liquid-vapor mixture

4. Evaporator or Heat Exchanger that Cools The Carnot Refrigeration Cycle Applying mass and energy rate balances Adiabatic Compressor Condenser or Heat Exchanger that Heats Expansion Valve replaced by Turbine

5. Carnot Refrigeration and Heat Pump Cycle (a) compressor power, in kW, (b) refrigeration capacity, in tons, (c) coefficient of performance Example: Carnot refrigeration cycle using R-134a as the working fluid is shown below. For a refrigerant mass flow rate of 0.08 kg/s, determine State h (kJ/kg) 1 Carnot 2 Carnot 3 Carnot 105.29 4 Carnot 98.85 x1=0.97297 h1=0.973(241.3)+(0.0267)(36.84)=235.77 0.3838=(1-x4)0.1481+x4(0.9253) x4=0.3033 h4=0.3033(204.46)+36.84=98.85 235.77267.97

6. The Carnot Refrigeration Cycle Wc= 267.97-235.77=-32.3 kJ/kg Qin= 235.77-98.85=136.92 Qout=267.97-105.29=-162.68 Wt=105.29-98.85=6.44 COP_HP=162/(32.3-6.44)=6.26 COP_Ref=136.92/(32.3-6.44)=5.29 COP_HPT =TH/(TH-TL)=312.39/49.48=6.314 COP_Ref=TL/(TH-TL)=262.91/49.48=5.31 COP calculated based on temperature ratios and those calculated based On heat transfer and work done are identical within property tables accuracies.