Soft-optimized tests of R-410A alternative refrigerant R-32 in a split system heat pump. By Stephen Li Jan

Transcription

1 Soft-optimized tests of R-410A alternative refrigerant R-32 in a split system heat pump By Stephen Li Jan

2 AREP candidates Flash point ( o C) Comparison of properties R32 L41a R290 R410A 240 o C (COC) -104 o C (COC) Oil compatibility POE Mineral POE Temperature glide ( o F) ASHRAE safety class A2L A2L A2 A1 NA GWP 675 < Impact on system at 40/100 F R32 L41a R410A Comp discharge temp +22 o C +3 o C Baseline Suction pressure 1.8% -10% Baseline Discharge pressure 2.3% -9% Baseline Pressure ratio 0.5% 1% Baseline Capacity 7.6% -6% Baseline Efficiency 1.1% 4% Baseline R32 has similar operating temp and pressure as R410A; R32 has 50% more specific enthalpy than R410A; R32 has higher comp discharge temp, +30 o F due to big adiabatic index; R32 has better thermal conductivity of liquid; R410 A T evap ( o F) T suc ( o F) P suc (psia) P dis (psia) γ k (btu/hr ft F) 0.059/ (liquid/vapor) R / (liquid/vapor) R / (liquid/vapor) ρ suc (lbm/ft 3 )

3 R32 test done by others test unit R410A DC Honeywel inverter ductless l split HP Daikin OD condition A B 109 H1 H2 14 Qc ref EER Tdis Qc Tdis Qh Tdis Qh EER EER COP COP COP Tdis (btu/hr) (F) (btu/hr) (F) (btu/hr) (F) (btu/hr) (F) baseline R41 0A improvement R32 +3% +2% % -1% baseline R improvement R22 DC inverter R32 half vs. R410A cap +7% % improvement full R32 vs. R410A cap Emerson 3T HP improvement +3.3% -1.4% +2.6% - 1.5% +10% % % % % +0.9 % +3.5% -0.8% Other literatures shows 3-6% improvement of capacity and 2-3% improvement of EER of R410A 3

4 Test objective What to learn in test? & What questions to answer after test? Short term: What s the difference of R32 and R410A on system thermal performance at rating conditions & extreme conditions? Is R32 compatible to R410A system? Is there any additional design control needed? Does R32 cause more compressor dynamic and piping vibration at rating conditions & extreme conditions? To get the same capacity and efficiency, which components (HX, comp, piston, charge, etc.) need to be changed from R410A to R32? Long term: Can R32 be applied to all existing models? Or which existing models can use R32 with minor system modification? Would R32 cause any reliability risk compared to R410A? Is there any degradation of R32 system? Is it possible to get higher EER/COP by using R32 in the existing R410A system? What parts need to be changed to get higher capacity and higher efficiency? 4

5 Test combinations & steps Tests performed Test unit: SSZ140361BA (SN ) / AVPTC313714AA (SN ) R32 Test scheduled 7/27/12-8/5/12 in Intertek (Plano, TX); Baseline test - R410A w/ Emerson 5-ton GMC in-house, charge 186 oz; Soft-optimzed test - R32 w/ Emerson production 3-ton Intertek; Test steps N 2 pressure 300 psi+; Vacuum system to 300 μm; ID TXV was adjusted for SH O/E in cooling; Charge was optimized based on SC liquid; OD TXV was adjusted for SH in heating; ID high speed tap D, ON-ON-ON-OFF w/ static pressure 0.23 H 2 O; 5

6 Test setup & instrumentation T T#7 T #5 T#6 #15 T#16 P, T #18 4-way valve OD coil ID coil P, T #1 check valve piston check valve TXV comp dryer P, T #12 Sight glass P, T #24 accumulator P, T #11 m Flow meter OD ROOM P, T #23 ID ROOM cooling heating 6

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8 Test data locations In addition to regular locations of air side DB/WB data and refrigeration system, the following data locations are required: data locations in refrigeration system P T Ref. mass flow rate Comp discharge (#1) x1 x1 Comp suction (#24) x1 x1 OD coil common in (#5) x1 OD coil mid (#6) x1 OD coil out (#7) x1 After OD piston, SV (#11) x1 x1 Suction SV (#23) x1 x1 ID coil in (#15) x1 ID coil mid (#16) x1 ID coil common TXV bulb (#18) x1 x1 Before ID TXV (#12) x1 x1 x1 Total x6 x11 x1 8

9 REF PISTON TES T CHG W EER SEE PRESSURE PSI TEMPERATURE SH SH SH SC REF Q Q RAT H.B. AIR REF M ID OD CO HSP Q oz COP SUC O/E B/4 LIQ DIS SUC O/E B/4 LIQ DIS DIS SUC O/E O/C E Q AIR ND F REF EFF BASELINE R410A TEST WITH EMERSON PRODUCTION TXV R410 A R32 5T TXV T TXV R32 evaluation A % B % C % D CLF= 0.184; CD = 0.187; PLF = H H1C HLF=0.163; CD= H H % R32 TEST WITH EMERSON PRODUCTION TXV A % 3.8% 2.5% 1.3% B % 2.0% 1.1% 1.2% C % 5.2% 0.1% 7.1% D CLF=0.179; CD= % % H % 3.7% H % 1.4% -9.5% 1.5% H % 2.0% -8.3% 2.2% H1C HLF=0.152; CD= % H % 3.5% H % 6.9% % % % 4.8% 9

10 Piston size sensitivity REF PISTON TEST CHG BTUH AIR ID OD COND oz R32 R32 R32 BTU H REF TOTA L WAT TS ID EER PRESSURE PSI TEMPERATURE WAT TS SUC COP T O/E B/4 LIQ DIS C SUC T O/E B/4 LIQ DIS C 3T H TXV 3T H TXV 4 3T H TXV 3 SCF M DIS SUC O/E O/C REF RAT E Comp suction SH of R32 is sensitive to piston size, SH changes 7-12 o F with change of piston size; To get low comp suction SH of R32, piston size needs to be refined with smaller steps, e.g ; 10

11 Test p-h diagram 4.0% 3.5% 3.0% 3.8% R32 improvement in % over R410A Comp discharge temp (of) % 2.0% 1.5% 1.0% 0.5% 1.3% 2.0% 2.0% 1.2% 2.2% % A B H1 0 A B H1 Cap EER/COP R410A R32 11

12 Cd & SEER/HSPF System Data Base. Alt. Ratio Cooling Degradation Coefficient Cd Seasonal Energy Efficiency Ratio - SEER Heating Degradation Coefficient Cd Heating Seasonal Performance Factor - HSPF Cd of R32 is smaller than R410A, which helps improve SEER/HSPF further; 12

13 Observations of soft-optimized test Evap out SH of R32 is about 1-2 o F higher than R410A due to the open limitation of 3T TXV (fully opened); Comp suction SH of R32 is higher; ID Emerson TXV was fully opened in R32 test to make SH close to that of R410A test; R32 charge is ~70% of R410A, flow rate is ~67% of R410A; R32 cond & evap pressure are ~ 10 psi higher than R410A in both cooling and heating; R32 cooling performance is 4% better in capacity, 1-2% better in EER, & 5% better in SEER (w/ improved Cd); R32 heating performance is 2% better in capacity/cop & 8% better in HSPF (w/ improved Cd); R32 operates at extreme conditions (115 & 10 o F); Discharge temp & SH of R32 is ~10 o F+ higher than R410A; Comp suction SH of R32 is sensitive to piston size & valve modulation refined piston size & careful valve sizing and selection ; 13

14 Conclusions Conclusions R32 works in existing R410A system, including extreme conditions; R32 improves capacity by 4% and efficiency by 1-2%; Tdis of R32 is 7-29 o F higher than R410A; Pcond & Pevap of R32 is 10 psi+ higher than R410A; Charge of R32 is 30% lower than R410A; Flow rate of R32 is 33% lower than R410A; 14