CFC ALTERNATIVES FOR REFRIGERATION : MORE THAN 2 YEARS OF FIELD TRIALS

Transcription

1 CFC ALTERNATIVES FOR REFRIGERATION : MORE THAN 2 YEARS OF FIELD TRIALS P. WEISS, M. BARREAU Elf Atochem S.A Centre d'application de Levallois (C.A.L) 95, rue Danton Levallois Perret, FRANCE G. ROLOTTI Elf Atochem North America Research and Application Laboratory 900 First Avenue, PO Box 1536 King of Prussia, PA 19406, USA 1 - BACKGROUND Due to the revision of the Montreal Protocol (Copenhagen - November 1992), CFCs will be phased out at the end of The European Union (EU) has adopted a more severe position and will ban CFCs by the end of In order to face this challenge, Elf Atochem has developed a comprehensive range of CFC alternatives. Today, CFC-12 can easil be replaced by the FORANEQ 134a or the FORANEQ FX56 (retrofit) and R-502 by the FORANE 8 FX70 or the FORANEB FXlO (retrofit). During the last two years, Elf Atochem's new FORANE@ refrigerants have been intensively tested in the field, first, by compressor manufacturers, second, by equipment manufacturers and contractors. FORANEB blends are today recognized by major compressor manufacturers and are requested by major supermarket chains for retrofits. Large number of retrofits have been performed on various systems through a wide range of technology all over the world. This paper puts forwards a selection of representative experiences where Elf Atochem brought technical assistance and follow-up, in order to assess FORANE@ products performance. Upon these experiences, it appears that data and observations reported by contractors indicate that for technicians used to R-12 and R-502, the retrofit handling do not require field assistance from Elf Atochem. Finally, in all cases, superior or equivalent performance versus CFCs was permanently achieved with the Elf Atochem's marketed products. 65

2 2 - AVAILABLE OPTIONS For many years, the refiigeration and air-conditioning inmstry has heavily relied on R-12 applications such as domestic, commercial and transport refrigeration; stationary (centrifbgal chille and mobile air conditioning. 2.1 R-12 & R-500 Substitution: 0 HFC-134a has been almost universally adopted by the market for new installations to replace tho which were in the past designed with R-12. R-134a is a zero Ozone Depletion Potential (OD refrigerant and has a reduced green-house effect (the Halocarbon Global Warming Potenti;, HGWpl 90% lower than R-12 combined with remarkable energy efficiency). Therefore, Elf Ato& considers it as a long term solution leading to minimize the TEWI (Total Equivalent Warmil Impact) of the system. Applications where R-134a has been proved as hlly reliable in retrofitting R-12 systems inclui; centrifbgal chillers (ref# l), semi-hermetic reciprocating and screw compressors in refrigeration of a1 kinds and mobile air-conditioning systems (refx2). 0 However, retrofitting to R-134a is not the most suitable option for the conversion of hermet: systems (the change of the traditional mineral oil over polyolester lubricant is a major issue) or I low temperature systems (loss of cooling capacity when the evaporation temperature is below -25O( (13OF) ). For these purposes, Elf Atochem has developed a range of near azeotropic blends: th FORANEQ FX56 (R-409A) and the FORANE@ FX57, both blends based on HCFC-22, HCFC-12 and HCFC-142b7 formulated to be "drop-in'' products for the R-12 replacement (no oil chang necessary in most cases). R-409A is a very efficient option for commercial showcase retrofits ani domestic refrigeration maintenance. Besides, the FORANEQ FX57 is dedicated to transpor refrigeration (R-500 application) and low temperature systems such as freezers. Exhibiting an OD1 of only 0.05 and an HGWP of 0.3, both blends offer a 96 % reduction in ODP and a 90 % HGWI i reduction compared to R- 12. And according to the Copenhagen revision of the Montreal Protocol, HCFCs and therefore HCFC: based blends will be allowed to use for at least 20 years. 2.2 Substitution of R-502: 4 R-502 has been widely used in low & medium temperature commercial refrigeration and as well in transport and industrial refrigeration. HFC-143a based blends have been identified by leading fluid producers and considered by major compressor manufacturers as being the best candidates to replace R-502 in new equipment. They are long term solutions with zero ODP and lead to significant TEWI reduction (due to a GWP' reduction compared to R-502 and associated with excellent energy efficiency3) I * I refirs to R-Ii, HGWP ofr-ii IS I/'refers to COL GWP ojco2 is see rep5 66 1

3 Two prodtrcts can be considered : The FORANE@ FX70 (R-404A), near azeotropic blend based on HFC-125, HFC-134a and HFC- 143a, is seen by the market as the best R-502 match (can also be used to retrofit equipment, changing the oil). Equipment is now available for designing systems with R-404A. The FORANE@ FXlO (R-408A), near azeotropic blend based on HCFC-22, HFC-125 and HFC- 143a, is the easiest retrofit option. In the field, this product exhibits superior performance compared to R-502 and minimizes the oil issue (at the worst, an oil drain is needed) : a large number of tests was conducted keeping the original mineral oil (ref#3). It offers over 90 % ODP and 80 % HGWP reduction compared to R SEVERAL REPRESENTATIVE CASE STUDTES - All data released in this arficle through the followitig examples hase beer) validated for at least - 9 months by EvAtocheni - The retrofits selected in this paper were carried out using near azeotropic blends. These products must be liquid charged into the installations to ensure optimum performance and a quick refrigerant transfer, as it was done for example with the R-502. The FORAPE@ blends intended to installation retrofits, were formulated so in terms of thermophysical characteristics to match those of the CFCs they replace. No equipment change such as expansion device, line sizing or compressor modifications are necessary (ref ## 4) Retrofits usinp HCFC containiw blends Due to the fact that these blends contain HCFCs they are compatible with lubricants originally used in CFC containing systems, such as mineral (MO), alkyl benzene (AB) or semi-synthetic (blend of MO & AB) oils. They will perform as well as CFCs did. Sometimes, to obtain a better miscibility, alkyl benzene lubricant can be added to the mineral oil used in the installation. Therefore these HCFC containing products offer the lower retrofit cost option. Also, these blends can be used with polyolester (POE) lubricants if they are the preferred choice, - All these points show the high versatility of these refrigerants - Anyhow, Elf Atochem's recommendations should not interfere, in any case, with equipment manufacturers guidelines. Their procedures must be taken as a priority. 67

4 EXAMPLE 1 : FORANEBFX56 (R-409A) IN REFRIGERATED DISPLAY CABINETS FITTED WITH HERMETIC COMPRESSORS VERCO is a manufacturer of chiller and freezer display cabinets. VERCO's products have been :: for almost thirty years to the food and drink retail industry. R-409A was evaluated by VERCO replacement of CFC-12 in the servicing of their equipment. A two door R-12 cabinet was retrofitted to R-409A. The system was fitted initially with an Asl, hermetic compressor running with standard mineral oil and a capillary tube expansion device. system modification was undertaken. Characteristics of the svstem and performance comparison are shown below : Cabinet capacity Compressor model Displacement Refrigerant charge Y - Pull down rate from ambient 1.3 m-i T2134 A 17 cm3 R-12: kg / 0.95 Ib R-409A : kg / 0.85 Ib, R-12 : 0.37"C/min R-409A : 0.53"C/min We can notice that R-409A permits over 10% reduction in weight of the refrigerant charge ar:. significant improvement for the temperature pull down time. These findings have enabled VERCC approve the R-409A refrigerant as a CFC- 12 replacement for their application. EXAMPLE 2 : FORANEBFX56 (R-409A) IN LOW TEMPERATURE SYSTEMS HUBBAED Group sewice has successhlly carried out tests using R-409A. In this case, the R-4([ was chosen due to the evaporation temperature which is below -25 C (-13 F). Tests were conduc on transport refrigeration units. They include performance evaluation and compressor life test: Performance was assessed in various conditions (ATP standards) : box* temperatures down " 20 C (-4 F). * Refrigerated cornpartmerit 68

5 characteristics - and performance achieved are detailed below 0 Compressor: 0 Lubricant: 0 Unit cooling: SANDEN 508 driven at rpm Polyolester 2.9 kw ( C /OF) Box* temperature R-12 Ambient temperature I I Suction temperature f C 1 F) Suction pressure (bar a) Discharge pressure (bar a) Discharge temperature ( C /OF) Inlet condenser ( C /OF) Inlet condenser Outlet condenser ( C 1 F) Outlet condenser (bar a) Outlet evaporator ( C /OF) Outlet evaporator (bar a) Electrical heat input into box (W) Insulation value of box (W) Total system cooling capacity (W) I I I I I I I * Refrigerated compartmeiit

6 Comments : R-409A can be used to replace R-12 in retrofitting transport refrigeration applications and cal achieve satisfactory performance even with a box temperature of -20 C (-4 F) (Le, evaporate temperature below -25 C (-13 F) where R-134a is not a technically acceptable as a retrofit option). Important Remark : In this example, mineral oil should have been used. For policy reasons, HUBBARD Group ha chosen the POE oil due to its lubricant compatibility with both HCFC based and HFC or HFC base, refrigerants. Nevertheless this trial still confirms the versatility of the FORANE* FX56. EXAMPLE 3 : USING FORANE@FX~O (~-40s~) IN HERMETIC COMPRESSORS MIS4 an Italian producer of showcases and cold rooms has carried out comparative tests betweell R-502 and R-408A. Two identical cold rooms were respectively charged with R-502 and R-408A, Original mineral oil was retained in both systems. The svstem characteristics are shown below : I Comnressor model I ASPERA K I Displacement Cold room size (m3) Oil charge (cm3) Refrigerant charge (kg) R (3.8 Ibs) I I R-408A : 1.05 (2.3 1 Ibs) I The parameters also measured: evaporator ("C 1 F) condenser ("C 1 F) Suction temperature ("C 1 F) Discharge temperature ("C /OF) 225 V (A) R-502 R-408A I

7 Comments: 0 R-408A affords a 25 % (by weight) charge reduction of refrigerant, Compressor running time with R-408A was shortened compared to that of R-502, From ambient temperature (> 25 "C), a temperature of -20 C/-4"F was reached using R-408A within 3 hours instead of 4 hours when running with R-502. These observations indicate that R-408A has a better cooling capacity than R-502 and confirm the good match between R-502 and R-408A EXAMPLE 4 : USTNG FORANEBFXIO (~-408~) IN A CENTRALISED SEMI - HERMETIC COMPRESSOR PLANT The CASINO Corporation, one of the major French supermarket chains, chose R-408A to retrofit a R-502 low temperature installation with the following characteristics : e e 0 4 COPELAND D6RF compressors with a total cooling capacity of approximately 50 kw in the running conditions kg of refrigerant, A SEARLE RDD 8.12 Air cooled condenser, 8 Horizontal BONNET-NEUHAUS cabinets and 3 cold rooms (25 m3 each) were connected to the rack system. The original mineral oil was retained with R-408A. The svstem characteristics are shown below : L Evaporation temperature ("C /OF) Condensation temperature ("C /OF) Discharge temperature ("C /OF) Air off showcases temperature * ("C /OF) 385 V (A) R-502 R-408A / / / (') / (2)

8 I' Comments : More cooling capacity was obtained from R-408A combined with a lower energy consumption According to field experience, it permits an about 25-30% charge reduction on compact systems a n~ about 15% reduction on rack systems, Moreover, performance is improved in the majority of cases For instance, some supermarket chains claim that R-408A enabled 15% energy saving versus R-502 Also, field tests proved that R-408A compressor discharge pressure is equal or lower to that ofr 502. Therefore we car1 coriclirde that physical characteristrcs of R-408A are almost rdelltrcal to those of R Retrofit usinv HFC containing blends FORANEBFX70 (R-404A) ON A COMMERCTAI, ICE MACHIKE R-404A was selected by several OEMs as the best long term R-502 replacement due its close matcb, There is no need of major equipment redesign. Consequently, if customers desire to retrofi equipment with a zero ODP solution, the R-404A is the suitable option among HFC based blends. Many retrofits were carried out by contractors. When comparing with the HCFC based blend optior the major issue is the cost of the lubricant change due to the necessary flushes induced with the POI oil and the labor costs associated with it. In order to assess accurately how R-404A would perform on an existing R-502 installation, E: Atochem North America set up a test on a commercial ice machine at one of its R & D facilitie located in King of Prussia (Pennsylvania). A computer data acquisition system was installed with in flow thermocouples and milli-volt pressure transducers. The refrigerant charge was approx. 0.6 kg (1.3 Ib) and the ice production 3.6 kg per hour (7.9 Ibs/h: The mineral oil charge (0.6 kg) was removed from the system once baseline data was gathered wit R-502. The system (hermetic compressor 1/2 HP, vertical evaporator and air cooled condenser) wa flushed using R-502 until 1% of mineral oil was reached (3 04 could be accepted o the field). Larger installations such as rack systems should be flushed using polyolester lubricar instead of refrigerant ; 3 to 6 flushes are usually needed. R-404A was then introduced into the system (90 % of R-502 original charge by weight) and dat was gathered under the same conditions.

9 Parameters recorded are summarked below : - Power consumption per cycle (kw.h) Compressor discharge pressure (1) (bar a) Compressor discharge temperature(') ("C 1 F) Ice production (kg per hour / Ibs per hour) To difference evaporatod2) (K) TO difference condensedz) (K) R-502 R-404A I I (7.9) 3.6 (7.9) <3 <3-4 K larger with R-502 than NIA (1) Daily average (2) AT"= inlet TO - outlet TO 1 Comments : R-404A as compared to R-502 shows the same total ice output, no significant power consumption increase (approximately 1 %). There is little discharge pressure increase of about 5 %. But on the other hand, R-404A allows a lower discharge temperature. In general, there is no detectable operating changes from the user's point of view with either refrigerant. This example shows that R-404A may also be another option for retrofitting R-502 systems However, this product will perform better on a new installation designed for its use. Therefore this is the reason why EyAtochem does recommend to its customers the use of R-408A to replace the R-502 on existing systems because it is the easiest retrofit option GENERAL CONCLUSTON All examples described in this paper show that Elf Atochem has developed well adapted alternatives to CFCs refrigerants. Elf Atochem is able to supply by now HCFC & HFC based blends required by the market to replace smoothly all CFCs for refrigeration and airconditionning applications. Elf Atochem already produces, at an industrial level, all components, used pure or in blends, to satisfy the customer's needs and will be ready for the futur market's requirements. 73

10 ACKNOWLEDGEMENTS : We are gratefbl to all of the contractors, engineers and technicians who carried out the retrofit: provided the technical data. We are also gratefbl to companies mentioned in this paper for willing to perform retrofits FORANEB products and allowing us to publish the information. We would also like to address a special thank to John DAVEY, HRPR company (Elf Atocl exclusive distributor for the UK and Eire) for his active participation in the data collectior analysis. REFERENCES '%n example of successful CFC-I2 retrojjt with HFC-134a in the industrialjield", D. ARNAUD, Elf Atochem S A - G. ROLOTTI, Elf Atochem North America. 'Experience in retrofitting CFC-12 auto air conditioning Jystems with FORAN@ 134a : a system performance perspective", G. ROLOTTI and M. BRUBAKER, Elf Atochem North America. "An example of R-502 retrofit with FORAN@FXIO in commercial refrigeration", D. ARNAUD, J.C. TANGUY, P.WEISS - Elf Atochem S.A ; G. ROLOTTI, Elf Atocht North America ; M. VAUTHIER, A.F.P.A. "Test bench for near-azeotrope blenak used in commercial refrigeration", D. CLODIC -Ecole des Mines de Paris - Papers presented at the 1993 "International CF and Halon Alternatives Conference". "Comparison of performar7ces between R-J04A and R-50 7 used in commercial refrigeration ", D. CLODIC - Ecole des Mines de Paris - Paper presented at the 1994 PURDUE confer ******* 74