M o n t r e a l P r o t o c o l, O E W G - 3 0, G e n e v a, J u n e XIX/8 Report on HCFC Alternatives for High Ambient Temperature Regions Lambert Kuijpers Roberto Peixoto TEAP, co-chairs UNEP Refrigeration TOC

M o n t r e a l P r o t o c o l, O E W G - 3 0, G e n e v a, J u n e Decision XIX/8 At MOP-19 in Montreal, Decision XIX/8 was taken related to HCFC alternatives and specific climatic conditions: To request the TEAP to conduct a scoping study addressing the prospects for the promotion and acceptance of alternatives to HCFCs in the refrigeration and air conditioning sectors in Article 5 Parties, with specific reference to specific climatic conditions and unique operating conditions, such as those in mines that are not open pit mines, in some Article 5 Parties; To request the TEAP to provide a summary of the outcome of the study referred to in the preceding paragraph in its 2008 progress report with a view to identifying areas requiring more detailed study of the alternatives available and their applicability

M o n t r e a l P r o t o c o l, O E W G - 3 0, G e n e v a, J u n e Status 2010 Decision XIX/8 asks for guidance on the replacements for HCFC-22, which is a commonly used refrigerant under hot ambient conditions An RTOC sub-committee was assembled Delay in 2008 was due to problems in gathering accurate commercial product data from different countries Delay in 2009 was due to logistics, including difficulties in organising visits to South African mines Final report review at TEAP meeting 2010

M o n t r e a l P r o t o c o l, O E W G - 3 0, G e n e v a, J u n e High Temperatures in Many Places

M o n t r e a l P r o t o c o l, O E W G - 3 0, G e n e v a, J u n e A wide variety of candidate refrigerants (HFC, HFC based blends, HCs) can replace HCFC-22 in very hot climates Refrigerant selection pays attention to: Global Warming Potential, Cooling capacity at elevated ambient temperatures, Energy consumption, energy efficiency and related impacts on electricity supplies, availability of the refrigerant alternatives and suitable equipment. Refrigerants for High Ambient Temperature Air Conditioning

M o n t r e a l P r o t o c o l, O E W G - 3 0, G e n e v a, J u n e R-410A & R-407C Have Inferior Technical Performance to R-22 in AC In AC, the primary global replacement, especially for the dominant air-cooled designs, is R-410A One component of this blend, HFC-125, has a comparatively low critical point temperature (66 o C), resulting in a rapidly declining capacity and efficiency as condensing temperatures approach the critical temperature of the blend The same effect occurs with the blend R-407C

M o n t r e a l P r o t o c o l, O E W G - 3 0, G e n e v a, J u n e Elaborated Analyses For AC, condensing temperatures have been varied between 35 and 65 C 65 C condensation may occur at ambient temperatures in the range of C, if no precautions in design taken Even if 65 C condensing temperature would lead to substantial efficiency and capacity decreases, note that this temperature will only occur during part of a season, leading to much lower impact on annual performance Additional system design features (such as night operation combined with cold storage) have positive effects

M o n t r e a l P r o t o c o l, O E W G - 3 0, G e n e v a, J u n e Refrigerant Efficiencies at Various Condensing Temperatures 8

M o n t r e a l P r o t o c o l, O E W G - 3 0, G e n e v a, J u n e Application engineers will need to oversize equipment to compensate for the reduced capacity at the design ambient temperature In most cases R-410A or R-407C will need to be sized 5-10% larger than HCFC-22 equipment to compensate for the lower capacity at ambient temperatures up to 50 C The increased capital cost of oversizing the equipment will be about 3% for a 10% increase in capacity 9 Refrigerants for High Ambient Temperature Air Conditioning

M o n t r e a l P r o t o c o l, O E W G - 3 0, G e n e v a, J u n e The natural refrigerant HC_290 can replace HCFC-22 in low charge applications (small window and portable room air conditioners). When replacing HCFC-22 with HC-290 one needs to consider appropriate design changes to minimise the refrigerant charge of HC-290 to comply with the applicable codes and standards on refrigerant charges and flammability 10 Refrigerants for High Ambient Temperature Air Conditioning

M o n t r e a l P r o t o c o l, O E W G - 3 0, G e n e v a, J u n e HFC-32 and HFC-32 in blends are candidates for the longer-term replacement of R-410A The refrigerant HFC-32 is very moderately flammable HFC-32 has a GWP approximately one third of the GWP of R-410A and exhibits much better high ambient performance than R-410A Design changes required to convert from R-410A to HFC-32 are minor 11 Emerging Refrigerants for High Ambient Temperature Air Conditioning

M o n t r e a l P r o t o c o l, O E W G - 3 0, G e n e v a, J u n e Refrigerants for High Ambient Temperature Refrigeration The primary global replacement for commercial refrigeration is R-404A. The two components of this blend are HFC-125 and HFC-143a, both having relatively low critical temperatures causing a rapidly declining capacity and efficiency as condensing temperatures approach the critical temperature of the blend The study examines the suitability of R-404A, HCs, CO2 and ammonia as candidate HCFC-22 alternatives for very hot climates

M o n t r e a l P r o t o c o l, O E W G - 3 0, G e n e v a, J u n e For stand alone equipment, in high ambient temperature conditions, one high-GWP refrigerant (HFC-134a) and three low-GWP refrigerants (HC-600a, HC-290 and possibly HFC-1234yf) can be used with the current refrigeration technologies For centralized systems, low-GWP toxic and flammable refrigerants can be used in indirect systems conditions because there is no significant variation of the evaporation temperature 13 Refrigerants for High Ambient Temperature Refrigeration

M o n t r e a l P r o t o c o l, O E W G - 3 0, G e n e v a, J u n e HFC blends with high GWP, such as R-404A or even R-422D or R-427A can be used, but for those two blends the refrigerating capacity could be lower by about 5% and the efficiency could also be lower by 5-10% HCs, such as HC-290 and HC-1270, can be used at high ambient temperature since they exhibit relatively low discharge temperatures compared to HCFC-22. However, refrigerant quantities have to be limited for safety reasons 14 Refrigerants for High Ambient Temperature Refrigeration

M o n t r e a l P r o t o c o l, O E W G - 3 0, G e n e v a, J u n e The new low-GWP short-lived HFC-1234yf as well as new low-GWP blends can be expected to be commercialised during the next three years These new low-GWP refrigerants might also be used in indirect systems or cascading systems with CO 2 either as a refrigerant (in the low stage) or as a heat transfer fluid 15 Refrigerants for High Ambient Temperature Refrigeration

M o n t r e a l P r o t o c o l, O E W G - 3 0, G e n e v a, J u n e Refrigerants for Deep Mines The technology for deep mines is rather different than for high-ambient temperature operation The ambient heat rejection (refrigerant condensing) temperatures generally are less extreme in mines In addition, with low humidity, heat rejection typically employs water cooling towers rather than air-cooled condensers (i.e., the governing performance parameter is the wet-bulb rather than the dry-bulb temperature) 16

M o n t r e a l P r o t o c o l, O E W G - 3 0, G e n e v a, J u n e Refrigerants for Deep Mines A study tour of deep mines was made to South Africa in the second part of 2009 During the tour, leading mining companies, the engineering firms supporting them, researchers, and government contacts were consulted to verify the problems and confirm the solutions 17

M o n t r e a l P r o t o c o l, O E W G - 3 0, G e n e v a, J u n e Most newer mine chillers in the last decade have used HFC-134a, or ammonia (R-717) However, some older and some small mines use HCFC-22 Some newer installations use HCFC-123 to attain high efficiencies Some recent systems use water (R-718) as a refrigerant in a vacuum, with a vapour-compression flash cycle to produce ice slurries directly Some proposed systems would use air (R-729) in air- standard reverse Brayton cycles Refrigerants for Deep Mines

M o n t r e a l P r o t o c o l, O E W G - 3 0, G e n e v a, J u n e Summary for both AC & Refrigeration Some HFC blends that are alternatives for HCFC-22 have a low critical point temperature (66 o C), resulting in a rapidly declining capacity and efficiency as condensing temperatures approach the blend critical temperature

M o n t r e a l P r o t o c o l, O E W G - 3 0, G e n e v a, J u n e Summary (AC) In most cases equipment using R-410A or R-407C will only need to be sized 5-10% larger than HCFC-22 equipment to compensate for the lower capacity at ambient temperatures up to 50 C As a HCFC-22 alternative, HC-290 is suitable in low charge applications (<250 g) with appropriate design changes to comply with all applicable codes/standards HFC-32 is a candidate for the (longer-term) replacement of R-410A

M o n t r e a l P r o t o c o l, O E W G - 3 0, G e n e v a, J u n e Summary (Refrigeration) The use of indirect systems is possible at high ambient temperature conditions R-404A, or even R-422D or R-427A can be used, but the refrigerating capacity and the efficiency would decrease by about 5% and 5-10% HCs such as HC-290 and HC-1270 can be used in hot climates; they exhibit relatively low discharge temperatures compared to HCFC-22 The new low-GWP short-lived HFC-1234yf and new low- GWP blends can be expected during the next three years; they may also be used in indirect systems

M o n t r e a l P r o t o c o l, O E W G - 3 0, G e n e v a, J u n e Summary (Deep Mines) The ambient heat rejection (refrigerant condensing) temperatures generally are less extreme in mines. In addition, heat rejection typically employs water cooling towers rather than air-cooled condensers Most mine chillers in the last decade have used HFC- 134a, or ammonia (R-717) HCFC-22 old chillers can be mostly replaced by HFC-134a and ammonia chillers