Quote:
Originally Posted by buffalobillpatrick
Yes, I like the GEA Flat Plate HX online sizing software. I have used it several times over the last 5 yrs.
I have already bought 2X of the 4-Ton coax (snake) HX's from Surplus City.
Oversized for my 2-Ton R410a Copland scroll compressor.
As I will be using Propane, in my DIY W/W heat pump, I am trying to figure out how the oversized Condenser & Evaporator will effect Subcool & Superheat?
I have a 2-Ton R22 TXV with 0-50*F Superheat adjustment.
Am trying to figure out if SLHX, IHX will help COP or not?
Most of the many website I have researched say SLHX will help some, as Propane
needs very high Superheat at Compressor inlet using POE oil (33-35*C or K, note: as this is a delta temp, C or K are interchangeable)
and more Subcool should also help as fewer bubbles will be present at TXV.
Also lower temp. refrigerant entering Evaporator will pick-up heat faster.
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With oversized heat exchangers, your approach temperature on both sides should be very close. I believe both randen and mejunkhound both had pretty much nil superheat coming out of their evaporator heat exchangers and the system efficiency was a stellar figure. With a water source, the saturation temperature of the evaporator can be much closer to the actual loop or feed source water temperature due to the large surface area and high heat transfer capacity. This is a case not studied well by the institution, due to the obvious extra expenses of the gross oversizing. The compressor is the limiting factor here, it will be very happy with a low compression ratio to overcome, and your power draw will reflect the situation.