3 ms·

Most modern residential and commercial refrigerants aren't particularly flammable in air, they only score about a 1 on the NFPA 704 when under pressure. Also m

Most modern residential and commercial refrigerants aren't particularly flammable in air, they only score about a 1 on the NFPA 704 when under pressure. Also most technicians will "recover the charge" when possible during maintenance or decommissioning. There's been quite a bit of development in the equipment space in the past two decades. On the other end, you can for some applications, use "R-290" which is just highly pure propane. Typically waist high commercial ice cream freezers will use a fully sealed R-290 system. And finally there is also "ammonia phase change" refrigeration, which can be done with a compressor, but also a "generator" which is essentially just a propane or electrical boiler which creates the high pressure side of the system, also with no moving parts. You will typically find these in highly portable and mobile applications, such as RVs.

tdeck 4y ago
Here's a great website where the author charged an ordinary refrigerator with propane and got it working:http://www.sparkbangbuzz.com/els/refrig2-el.htm http://www.sparkbangbuzz.com/els/refrig2-el.htm Their other experiments are worth a read as well :)
- metadat 4y ago
  Why did they need to pinch the copper tubing shut?
  - tdeck 4y ago
    Here's my reading of it as a non-expert. The tubing isn't pinched shut, it's just pinched to restrict the flow. I believe it's to create a bottleneck where pressure can build up between the "hot side" and the "cold side" of the refrigerator. Before the pinch the compressor is driving gas into the pipe, where it meets resistance at the pinch point and compresses to liquid, shedding heat. Then after that point a narrow jet of compressed refrigerant squirts into a lower pressure part of the pipe and starts to evaporate, expanding and taking in thermal energy again. Of course, the refrigerator already has some valve to do this, but the author mentions that it may not be designed for the pressure differential needed for propane, so you can make your own with a pinched tube.
    - metadat 4y ago
      Thanks @tdeck, that was my naive guess, too. It seems so imprecise, I assumed it was a bad guess :) cheers bud.
  - c_o_n_v_e_x 4y ago
    To intentionally create a restriction, an orifice (auth uses the term expansion valve which is incorrect in this scenario). Liquid refrigerant flow is restricted when it flows through the orifice. This causes the pressure to drop which causes the refrigerant to flash/boil. While the refrigerant is flashing/boiling, it is absorbing heat from the surrounding environment.
- userbinator 4y ago
  You mean overcharged... see how it's frosting all the way back to the compressor? That both wastes energy cooling the outside of the cabinet and can damage the compressor if liquid refrigerant enters it. Ideally the charge amount should be such that the evaporator is fully frosted, but not much more than that.

tdeck 4y ago

Here's a great website where the author charged an ordinary refrigerator with propane and got it working:http://www.sparkbangbuzz.com/els/refrig2-el.htm http://www.sparkbangbuzz.com/els/refrig2-el.htm Their other experiments are worth a read as well :)

metadat 4y ago
Why did they need to pinch the copper tubing shut?
- tdeck 4y ago
  Here's my reading of it as a non-expert. The tubing isn't pinched shut, it's just pinched to restrict the flow. I believe it's to create a bottleneck where pressure can build up between the "hot side" and the "cold side" of the refrigerator. Before the pinch the compressor is driving gas into the pipe, where it meets resistance at the pinch point and compresses to liquid, shedding heat. Then after that point a narrow jet of compressed refrigerant squirts into a lower pressure part of the pipe and starts to evaporate, expanding and taking in thermal energy again. Of course, the refrigerator already has some valve to do this, but the author mentions that it may not be designed for the pressure differential needed for propane, so you can make your own with a pinched tube.
  - metadat 4y ago
    Thanks @tdeck, that was my naive guess, too. It seems so imprecise, I assumed it was a bad guess :) cheers bud.
- c_o_n_v_e_x 4y ago
  To intentionally create a restriction, an orifice (auth uses the term expansion valve which is incorrect in this scenario). Liquid refrigerant flow is restricted when it flows through the orifice. This causes the pressure to drop which causes the refrigerant to flash/boil. While the refrigerant is flashing/boiling, it is absorbing heat from the surrounding environment.
userbinator 4y ago
You mean overcharged... see how it's frosting all the way back to the compressor? That both wastes energy cooling the outside of the cabinet and can damage the compressor if liquid refrigerant enters it. Ideally the charge amount should be such that the evaporator is fully frosted, but not much more than that.