EcoRenovator - View Single Post - Evaporator sizing

stevehull · 12-20-13, 11:36 AM

Acuario,

There is a point where making the evaporator too large and you loose a lot of efficiency. Take this to the extreme to make the point.

Imagine a standard 36000 BTU (3 ton) air conditioner with a standard evaporator. Now, put in place an evaporator the size of a house. The gas that fills the evaporator has expanded almost to room pressure and it has long given up all the latent BTUs. Yes, it is cooled slightly more than say an evaporator the size of a kitchen and only slightly more than an evaporator the size of a bed.

The point being that the pressure - BTU - cooling curves are not linear, but are S shaped. Evaporators work on the linear part of the sigmoid curve. Beyond that and the change in pressure vs temp curve goes rather flat.

Also, imagine the volume of refrigerant you would need!!

Does this make sense?

Steve

12-20-13, 11:36 AM	#3
stevehull Steve Hull Join Date: Dec 2012 Location: hilly, tree covered Arcadia, OK USA Posts: 826 Thanks: 241 Thanked 165 Times in 123 Posts	Acuario, There is a point where making the evaporator too large and you loose a lot of efficiency. Take this to the extreme to make the point. Imagine a standard 36000 BTU (3 ton) air conditioner with a standard evaporator. Now, put in place an evaporator the size of a house. The gas that fills the evaporator has expanded almost to room pressure and it has long given up all the latent BTUs. Yes, it is cooled slightly more than say an evaporator the size of a kitchen and only slightly more than an evaporator the size of a bed. The point being that the pressure - BTU - cooling curves are not linear, but are S shaped. Evaporators work on the linear part of the sigmoid curve. Beyond that and the change in pressure vs temp curve goes rather flat. Also, imagine the volume of refrigerant you would need!! Does this make sense? Steve __________________ consulting on geothermal heating/cooling & rational energy use since 1990 Last edited by stevehull; 12-20-13 at 01:20 PM..