คุณเจ้าหน้าที่ไปอ่าน paper พวกนี้ให้หมดก่อน แล้วค่อยมาคุยกันต่อ อ่านให้เข้าใจ อย่าตีความผิดหรือหลงประเด็น หรือตีความเกินกว่าที่ paper กล่าวถึงอีกล่ะ
REsearch ของฝรั่งเรื่องความปลอดภัยของการใช้ propane และสารในตระกูลติดไฟเป็นสารทำความเย็น ละเอียดมาก
การทดสอบการรั่วของสารทำความเย็นในตระกูลเดียวกัน ยืนยันว่าแม้มันจะติดไฟ แต่ความเสี่ยงถือว่ามีน้อยมากในการใช้ในระบบทำความเย็นขนาดเล็กถึงขนาดกลาง อ่านใน link ข้างล่างนี้ ให้ดูที่หน้า 4 ตรง conclusion
ถ้าข้อมูลไม่จุใจ ยังอยากอ่านอีกล่ะก็ ตาม link ข้างล่างนี้ไปครับ
In 1992, Greenpeace (Germany) campaigned for an alternate technology, which would be both ozone friendly and without GWP. The technology which re-emerged as the most suitable for these purposes was an old one, which used hydrocarbons.
At present hydro carbon technology makes use of one of the two compounds, viz. isobutane (R600a) or a blend of propane and isobutane (R290/R600a) as refrigerant and usually cyclopentane for insulation. The most important advantage is their compatibility with mineral oils as against HFCs, which require synthetic lubricants. Additional advantage is of retrofitting in old units without much incremental costs.
Most importantly, the HC technology provides an economically viable option to the Article 5 countries to leapfrog from CFCs to HCs rather than to invest in HCFCs or HFCs which would soon have to be phased out.
In 1994, German manufacturer dkk/FORON, along with Greenpeace, launched the first HC based refrigerator using a blend of propane and isobutane. This greenfreeze technology made a soaring impact on the German market forcing established manufacturers such as Bosch-Siemens, Liebherr, AEG/Electrolux and Whirlpool to adopt the HC technology.
These manufacturers opted for pure isobutane (R600a) as a single component refrigerant, which is easy to handle and is of advantage while designing two temperature refrigeration appliances (refrigerator-freezer combines). Liebherr was the first company in 1994 to convert their foaming lines to Pentane as a blowing agent replacing CFC11. Over the years the HC based refrigerator has captured more than 10% of CFC free domestic refrigerator market, mainly in Germany, Austria, Switzerland, the Netherlands and other Scandinavian countries.
Companies like Matsushita and Sharp of Japan have gone half-way by converting to pentane blown insulation foam. Similarly in Australia, Fisher & Paykel, a refrigerator manufacturer are blowing foam with cyclopentane.
Table 2: Comparison of Ecofrig technology (column 1 & 2) with HFC134a technology (column 3).
R600a Propane/Isobutane R290/R600a Hydrofluorocarbon HFC134a
ODP 0 0 0
GWP* 3 3 3400
Energy efficiency of Compressor Higher than mixture and HFC134a
Retrofitting CFC12 refrigerator without changing compressor No Yes No
Flammability Yes Yes No
Safety Provisions Yes Yes No
Noise level of of compressors Higher than mixture and HFC134a Higher than isobutane
Sensitivity to contamination and manufacturing process conditions Insensitive: Production standard same as CFC12. Insensitive: Production standard same as CFC12. Highly sensitive:
Major Manufacturing changes required
ผลการทดสอบว่า R290+R600a ใช้ทดแทน R12 ได้
A computational model with the objective of simulating the performance of an ideal automotive air conditioning system, working with several refrigerants, is presented. The main function of this model was to determine the most suitable alternative refrigerant for R-12. Some assumptions about the losses and irreversibilities were embodied in this model for more realistic results. The effects of several parameters on system performance and compatibility were investigated, including evaporating temperature, condensing temperature and compressor rotational speed. Five refrigerants were studied by this model, including R-12, R-134a, R-290, R-600a and a mixture of propane and isobutane R290/R600a (62/38, molar percentage). The model predicted that the mixture (R290/R600a) was the most suitable alternative for R-12 and that several modifications should be performed when the other alternative refrigerants are used in the R-12 system. The major part of this work was an experimental investigation for the use of R290/R600a as a drop-in alternative for R-12 in a prototype automotive air conditioning system. Ninety-two (92) tests were conducted on both refrigerants to study the effect of four parameters on system performance. These were outdoor air temperature, cooling load, compressor rotational speed and the soaking temperature. Three outdoor air temperatures were considered, 35, 40 and 50 °C. Six rotational speeds were employed, 700, 1000, 1500, 2000, 2500 and 3000 rpm, whereas four cooling loads were simulated in the evaporator chamber, 1000, 2000, 3000 and 3500 W. The evaporator chamber was soaked at five temperatures, 45, 50, 55, 60 and 65 °C. Two types of tests were performed, including single operation mode tests and multi-operation modes tests. There was close similarity between the performance of the R290/R600a mixture and R-12 with superiority for R-12 in the working pressures, energy consumption and the COP values, whereas the mixture (R290/R600a) outperformed R-12 in the subcooling, superheating, evaporator discharge air temperature and the cooldown time. The results of this work showed good agreement with the experimental and theoretical results available in the literature
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