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Old 01-21-14, 06:17 PM   #19
Thepprof
Lurking Renovator
 
Join Date: Jun 2012
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Default Larger evaporator

Quote:
Originally Posted by Acuario View Post
Now I have my defrost circuit monitoring the temperature on both sides of my evaporator I got to thinking, would a bigger evaporator be more efficient?

Heat pumps obtain their energy from low grade heat (the atmosphere) and 'convert' it into high grade heat using a compressor. The warmer the temperature of the gas entering the compressor the less hard the compressor has to work to compress the gas and raise its temperature.

Whilst monitoring my evaporator I have seen variations of temperature difference of between 1C and 6C depending on the ambient temperature. The exit temperature is invariably less than ambient temperature (it approaches it at very low temperatures).

So, my thought is, with a larger evaporator there would be extra surface area (and time) for the refrigerant to absorb heat from the atmosphere, hence improving the efficiency of the heat pump.

Has anyone tried this? The argument seems sound but does it work in practice?

I have a machine with a dead compressor but a perfectly serviceable fan and evaporator and I'm tempted to try it out but would love to hear any feedback on my proposed hack before getting out the cutters and brazing torch.

Acuario

Hi; The laws of physics and thermodynamics have a basic rule regarding heat transfer or movement. From hot to cold and directly related to the difference of temperatures from one medium to another and inversely to the insulation value of the medium. Aluminum and copper transfer heat rapidly while wood fiber glass of course insulate' Larger coils on either end of the cycle means more efficiency. Note that most late model ac units outside units are huge.
I don't know enough to tell you how to balance the internal workings of this switch. I notice that my unit has 4 banks of coils with a txv to each while old units had basically 1 metering device to the coil. Owen
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