Air Source Heat Pump - temp of refrigerant leaving evaporator

[anup]

Hi Technocrats,
I am trying to design air source heat pump for water heating application. Though I have an experience in selling heat pump, but not designed nor have information.
Cosider the example:
Refrigerant-R22
Evaporating temp - 4 deg. C. (39.2 F)
Ambient air temp (flowing through evaporator) - 30 deg. C (86 F)
Temp drop across evaporator - 7 deg. C. (44.6 F)
My query:
1. How to design evaporator?
2. How to calculate heat content in refrigerant gas at evaporator outlet?
3. How to calculate, refrigerant gas temp leaving evaporator?

[chemi-cool]

Hi anup,

I am not a designer but a welded plate HE is the best for your application.

You will need to provide more details if you want some free advice, like, information on the water side.

Chemi:)

[anup]

Dear Chemi,
Thanks for your reply. I was coming to that point but at a later stage.
Water part will come while designing condensor. but before that I need to understand evaporator design, based on which I can give you heat content in discharge gas (from compressor).
Meanwhile, could you pl. give some basic guidelines for condensor?
Anup

[penair]

hi Anup,
How many litres of water are you heating? will the water be in a insulated storage tank? how many kiloWatts compressor capacity do you require to heat the water, what is your cut in / cut out water temperature degrees C? The problem you may find is that up to a certain water temperature, Eg. up to 40 degrees C condensing the refrigerant is not a problem, after that the condensor may become just a subcooler and therefore the eficiciency or COP of your system will fall very quickly.