coldkeeper1
Mechanical
- Apr 26, 2008
- 12
I mostly work in design/installation of commercial HVAC systems. That´s why I don´t see myself like a transport refrigeration engineer. But I hope some of you are. These are the facts.
I friend of mine has come to me with an emergency. He recently bought about 8 used refrigerated trucks for his seafood distribution business. Since most units exhibited above normal temperature pull down times, his refrigeration tech recommended a compressor retrofit for each unit with a somewhat larger compressor. Results: improved pull down times but higher high side operating pressures (of course, since I guess they are using the same condensers). Now the new compressors have begun to fail. He´s already planning to sue this individual, but he needs solutions quickly. There is no way to simply improve condensing surface or air flow mainly because of space availability. I´m trying to figure out some kind of cooling method for the compressor itself. I don´t like the idea of reducing superheat for better compressor cooling, so I´m looking for other scheme. I observed a liquid injection system in a similar unit from another manufacturer. Most likely this system uses an orifice to meter the amount of liquid, not just the opening or closing of a solenoid valve, but I´m not sure. I guess it must be a temperature controlled injection, but any homemade solution would be pressure controlled, with off-the-rack components. Could someone give me a hand with this design ? Thank you.
I friend of mine has come to me with an emergency. He recently bought about 8 used refrigerated trucks for his seafood distribution business. Since most units exhibited above normal temperature pull down times, his refrigeration tech recommended a compressor retrofit for each unit with a somewhat larger compressor. Results: improved pull down times but higher high side operating pressures (of course, since I guess they are using the same condensers). Now the new compressors have begun to fail. He´s already planning to sue this individual, but he needs solutions quickly. There is no way to simply improve condensing surface or air flow mainly because of space availability. I´m trying to figure out some kind of cooling method for the compressor itself. I don´t like the idea of reducing superheat for better compressor cooling, so I´m looking for other scheme. I observed a liquid injection system in a similar unit from another manufacturer. Most likely this system uses an orifice to meter the amount of liquid, not just the opening or closing of a solenoid valve, but I´m not sure. I guess it must be a temperature controlled injection, but any homemade solution would be pressure controlled, with off-the-rack components. Could someone give me a hand with this design ? Thank you.