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Air-to-air AC and HP module

asked 2017-03-21 20:02:20 -0500

dedaca gravatar image

updated 2017-05-04 09:04:47 -0500


I am trying to find a program/script that I can extract from energy+ source code on GitHub that can mimic a simple air-to-air AC for cooling in the summer but could also be used in the winter for heating - i.e. Reversing the flow of refrigerant and used as air-to-air heat pump.

  1. Is the DX air cooling coil suitable for this? If so, can I use the same for the HP mode?
  2. Where is the cooling capacity modifier curve function of temperature taken from? And what about the one for heating?
  3. Where is the nominal COP and Capacity taken from? Is it from any of the manufacturer's specs?
  4. Where can I find which type of AC/HP make and model can be modelled using this method?

In the end, I will simply need to use the simplest model out there that can model an AC and HP capacity and cop as a function of air temperature and humidity, it does not need to be energy-plus’s but this is what I found so far. It just needs to be open source and with a manual describing the assumptions and equations it is using so that I can understand what it is doing.

If anyone has any answers/suggestions I'd be grateful.


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answered 2017-03-22 08:30:28 -0500

The heat pump model in EnergyPlus is actually 2 coil models that represent the single coil in a typical heat pump. One coil models the cooling performance, the DX cooling coil, and the other models the reverse cycle for heating, the DX heating coil. These models are found in the source code in The CalcDoe2DXCoil function models the cooling coil while the CalcDXHeatingCoil models the heating coil. Only one of these coils is active at any given time. The documentation and equations for each are found in the Engineering Reference document under Single-Speed Electric DX Air Cooling Coil and Single-Speed Electric Heat Pump DX Air Heating Coil.

Answers to your questions:

  1. Yes, for the cooling model. This model cannot be used to model heating operation.
  2. The cooling/heating capacity modifier curves are taken from manufacturers data. They represent how the capacity changes when outdoor conditions and entering coil air conditions change. There are also performance curves for energy input and changes in performance for variation in air flow rate and part-load performance.
  3. COP is also found in manufacturers literature.
  4. This is an empirical coil model that can represent virtually any HP on the market today. The performance is based on manufacturers data that show how "system" performance changes with changing conditions (temperatures, air flow, part-load cycling, etc.)
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Asked: 2017-03-21 20:02:20 -0500

Seen: 205 times

Last updated: Mar 27 '17