sizing equipment for a recirculated air loop

[D Marini]

Dear all,

In my project, I need to design and test and air-to-water heat pump unit working in heating mode.
For the purpose of this it was suggested from the team to create an recirculated air loop on the evaporator side of the heat pump.
On this loop we think to put an electric heater a humidifier, and a cooling coil.
The purpose of the loop is to supply air at the evaporator side at a different range of temperature and humidity.
The heat pump is supposed to have a heating capacity output 9 kW and and evaporator air flow rate of 1600 m3/h.

does any one has had any similar experience or suggestions how to proceed.

any help would be appreciated.

Kind Regard,
D Marini

 

[GT-EGR]

Haven't had any experience doing this because in a normal installation this is just wasting energy.

That being said, it sounds like you have all the basic components you need to create a good variety of entering air dry bulb and wet bulb conditions - heating, cooling, dehumidifying by cooling, and humidifying.

Keep in mind you haven't mentioned the water side either. You need to have the ability to keep the water temps and flowrates constant or else your test results won't be a direct comparison to eachother since the heat pump will perform better or worse just based on the water side variation alone.

 

[GT-EGR]

Your question is pretty broad, but in short I would consider the following.

If you are just testing the heating capacity, you really have no need to vary the humidity of the loop. The air moisture level doesn't have a significant impact (or even any really) as far as heating capacity, heating is just a sensible heat input.

You basically just need to install a cooling coil, that is sized identically (but in reverse) to the heating output of your heat pump. Ideally it's a chilled water coil, or if you have to do DX, you need a split system with lots of turndown capabilities, so that you can specifically control the output from your cooling coil.

You should start off and determine what your test procedure is exactly, and what conditions and range you are trying to simulate. Then you should also check that against what your heat pump is actually capable of as far as airflow modulation and heat output modulation. Once you know all that, you have to get a cooling coil selected that can most closely match all the different operating scenarios you have. But again, you are basically just selecting the exact opposite of your heating performance in a cooling coil, at identical airflows.

 

[lukaiENG]

Certified HVAC testing facilities have the sort of arrangement you are looking for.
They generally have a large test chamber which they heat/cool/humidify to get the right entering/ambient conditions. The capacity of the chamber conditioning system is generally a lot larger than the capacity of the equipment being tested, this is allow closer control of space conditions which would most likely be hard to stabilize if you were to equally match capacities.