Center for Environmental Energy Engineering Department of Mechanical Engineering University of Maryland College Park, MD

Transcription

1 System Drop-In and Soft Optimization Tests of R-40A Alternative Refrigerants in Split System Heat Pump Jan. 204 Abdullah Alabdulkarem, Radia Eldeeb, Yunho Hwang, Vikrant Aute, Reinhard Radermacher Center for Environmental Energy Engineering Department of Mechanical Engineering University of Maryland College Park, MD

2 Contents Objectives Schematic of test facility Test conditions Performance comparison of R40A vs. alternative refrigerants Simulation results Conclusions 2

3 Objectives Evaluate the performance of an air conditioner and a heat pump using low GWP refrigerants and compare the results against R40A Drop-in tested refrigerants are: R2 L4A D2Y60 Perform soft-optimized system tests to match the capacity to that of R40A

4 Properties of R40A and Low GWP Refrigerants Parameter Unit R40A R2 D2Y60 L4A Temperature C Sat. Vapor Pressure kpa Liquid Density kg/m Vapor Density kg/m Latent Heat kj/kg Liquid kj/(kg-k) Specific Heat Liquid Thermal mw/(m-k) Conductivity Temperature Glide K Liquid Viscosity µpa-s Significant thermophysical property differences 8.68 Vapor Viscosity µpa-s.7 between 2.7R40A 4and alternative refrigerants Vol. Cooling Capacity kj/m Critical Temperature C ct/h fg

5 Thermodynamic Model 40 o C condenser temperature and 0 o C evaporator temperature 70% compressor efficiency, 27. cm displacement volume o C superheat and 2 o C subcooling 2 6 Capacity (kw) 0 8 COP R40A R2 D2Y60 L4A R40A R2 D2Y60 L4A

6 Schematic of Test Facility 6

7 Heat Pump Unit Compressor Single Speed, Scroll Compressor Nominal Cooling Capacity Tons Rated SEER 4 Rated HSPF 8.7 Expansion Device TXV for Cooling / Orifice for Heating 7

8 Test Test ASHRAE Standard 6- and Extended Indoor Outdoor db ( o C) wb ( o C) db ( o C) wb ( o C) Operation Extended 46. Steady State Cooling A.4 Steady State Cooling B 26.7 NA Steady State Cooling C Steady State Cooling, Dry Coil D Cyclic Cooling, Dry Coil High Temp Steady State Heating High Temp Steady State Heating Low Temp Steady State Heating Extended NA Steady State Heating High Temp. Cyclic Cyclic Heating Frost Acc Steady State Defrost 8

9 Drop In Tests

10 Steady State Cooling Test Results R40A R2 D2Y60 L4A R40A R2 D2Y60 L4A Capacity (kw) COP 2 4 Extended A B C Extended Ref. vs. R40A R2 D2Y60 L4A Optimum Charge -% -% -% Avg. Cooling Capacity % -8% -7% Avg. Cooling COP -% -4% -% A B C 0

11 Steady State Heating Test Results. R40A R2 D2Y60 L4A. R40A R2 D2Y60 L4A. Capacity (kw) COP Extended Low Temp. High Temp. 2 High Temp.. Extended Low Temp. High Temp. 2 High Temp. Ref. vs. R40A R2 D2Y60 L4A Avg. Heating Capacity 4% -4% -% Avg. Heating COP -% -2% 2%

12 Drop In Tests Conclusions Charge reduction for all refrigerants compared to R40A R2 Capacity outperformed R40A COP can outperform R40A with optimized compressor D2Y60 Low COP and capacity Low discharge temperature L4A Capacity matched R40A for heating only COP matched R40A Highest values for SEER and HSPF compared to R40A 2

13 Soft Optimized Tests

14 Soft Optimized Tests Plan Refrigerants Challenge Soft- Optimization Tests Soft-Optimization (Long Term) R40A Baseline - TXV for Heating R2 D2Y60 Compressor outlet temp., Slight COP degradation Low capacity - TXV for Heating, Larger Compressor TXV for Heating, Optimized Compressor Optimized Heat Exchangers L4A Two-phase suction TXV for Heating Optimized Heat Exchangers 4

15 Steady State Cooling Test Results R40A D2Y60 Drop In D2Y60 Soft Opt 2 R40A D2Y60 Drop In D2Y60 Soft Opt 0 4 Capacity (kw) 8 7 COP Extended A B C Extended A B C

16 Steady State Heating Test Results R40A D2Y60 Drop In D2Y60 Soft Opt 4 R40A D2Y60 Drop In D2Y60 Soft Opt 2 4 Capacity (kw) COP Extended Low Temp. High Temp. 2 High Temp. Extended Low Temp. High Temp. 2 High Temp. 6

17 L4A Soft Optimized Tests 4 L4A Drop In L4A Soft Optimized 2 Superheat (K) Extended Low Temp. High Temp. 2 High Temp. 7

18 Steady State Heating Tests R40A L4A Drop In L4A Soft Optimized. R40A L4A Drop In L4A Soft Optimized Capacity (kw) COP Extended Low Temp. High Temp. 2 High Temp.. Extended Low Temp. High Temp. 2 High Temp. 8

19 Cyclic Heating Test R40A w/ Orifice L4A TXV Orifice Capacity (kw) 7 Capacity (kw) Time (min.) Heating- Power Air Side Consumption (kw-hr) (kw-hr) COP Heating Load Factor (HLF) Degradation Coefficient (C D ) HSPF R40A L4A Difference (%) Time (min.)

20 Simulation of Drop In Tests 20

21 System Model in VapCyc Condenser and evaporator are CoilDesigner components Compressor is 0 coefficient database compressor model 2

22 Numerical Capacity (kw) Numerical Capacity (kw) Numerical Capacity (kw) Preliminary Simulation Results R40A R2 D2Y60 L4A % Error Lines Experimental Capacity (kw) Experimental Capacity (kw) Experimental Capacity (kw) Cooling Tests Numerical COP Heating Tests Numerical COP Experimental COP Experimental COP 22

23 Conclusions Using larger compressor for D2Y60 enhanced capacity but deteriorated COP Using TXV for L4A enhanced HSPF without significant change in steady state test results Simulation predicted the experiments well except in low and extended heating tests 2

24 Questions/Comments? Thank you! 24

25 Frost Accumulation Test R40A w/ Orifice L4A w/ TXV 7 7 Capacity (kw) Heating-Air side (kw-hr) Average Heating Capacity (kw) COP R40A L4A Difference (%) Capacity (kw) Time (min.) Time (min.) 2

26 Cyclic Cooling Test R40A D2Y60 Soft Optimized Capacity (kw) 7 Capacity (kw) Time (min.) Time (min.) Cooling- Air Side (kw-hr) Power Consumption (kw-hr) COP Cooling Load Factor (CLF) Degradation Coefficient (CD) SEER R40A D2Y Difference (%)

27 Capacity (kw) 7 - Cyclic Heating Test R40A Time (min.) Heating- Power Air Side Consumption (kw-hr) (kw-hr) COP Heating Load Factor (HLF) Time (min.) Degradation Coefficient (C D ) HSPF R40A D2Y Difference (%) Capacity (kw) 7 - D2Y60 Soft Optimized

28 Refrigerant Temperature in A Test 0 R40A R2 D2Y60 L4A Temperature ( C) Compressor Suction Compressor Discharge Condenser Outlet Expansion Device Inlet Evaporator Inlet (Calculated) Evaporator Outlet 28

29 Compressor Discharge Temp. and Mass Flow Rate in Cooling Tests Discharge Temp. ( C) R40A R2 D2Y60 L4A Ref. Mass Flowrate (g/s) R40A R2 D2Y60 L4A 0 Extended A B C Extended Ref. vs. R40A R2 D2Y60 L4A Avg. Compressor Disch. Temp. 4 C -4 C 7 C Avg. Ref. Mass Flow Rate -% -6% -2% A B C 2

30 Compressor Efficiencies Isentropic Efficiency R40A R2 D2Y60 L4A Extended A B C Volumetric Efficiency R40A R2 D2Y60 L4A Extended Ref. vs. R40A R2 D2Y60 L4A Avg. Isentropic Efficiency -6.% -.8% -.% Avg. Volumetric Efficiency -4.4% 0.% -2.4% A B C

31 SEER and HSPF 4 2 SEER (Btu/W-hr) HSPF (Btu/W-hr) R40A R2 D2Y60 L4A Ref. vs. R40A R2 D2Y60 L4A Avg. SEER -.% -8.% -2.4% Avg. HSPF 2.8% 6.% 6.7%