PDA

View Full Version : Air source heat pump designing issues







samux12
06-08-2013, 02:20 PM
Hello guys,

Currently I'm working on prototype air/water reverse heat pump.
In the picture below is shown the main hydraulic scheme of this heat pump.
10621

Due to the variable speed compressor and not permanent working load, I thinking about installing liquid receiver. Furthermore Coil's and BPHE's volumes differs twise ( 4,5 vs 2 ltr), so for reverse system liquid receiver is mandatory. I'm right or not?

For the better efficiency I want to install subcooler in the liquid line (8). What's your oppinion about subcoolers in heat pumps?

For the heating mode the system should work properly I guess, but the problems should occur in cooling. In the cooling mode subcooler won't work.

What can you say about this scheme? What's your recomendations about components added?

Moreover, I can't find any producers of Surge liquid receivers. In the reverse refrigerant circle it fits much better than the conventional one.

samux12
06-08-2013, 02:34 PM
Bigger size scheme

10622

samux12
08-08-2013, 09:58 AM
Can anybody tell me about Subcooler's application i heat pumps. The system would be charged with R410A refrigerant.

I have read many articles about its possitive and detrimental influence depending on refrigerant type, but I couldn't find any information about Subcooler performance with R410A refrigerant.

What do you think, is it worth to do use it in air to water heat pumps?

The Viking
08-08-2013, 10:18 AM
I would have thought that the use of a subcooler depends on the system design more than anything else.

In real life a subcooler is an extension of the condensor, so if your condensor is large enough there wouldn't be any gains on adding a subcooler. On the other hand, if you got two heat demands for example heating and hot water then splitting the condensor up might be a valid design point even if thought has to go in to the varied demands and what will happen when there only is demand for heating OR hot water.

The other use of the subcooler, using it refrigerant to refrigerant, could be to ensure there is enough superheat when the refrigerant enters the compressor, allowing for the system to run at lower ambient temperatures but in this case it could reduce the duty available for heating. Again, a system design preference.

In your case, what do you want to achieve by using a subcooler?

:cool:

samux12
02-09-2013, 02:50 PM
I want to extend compressor working envelope to the lower side as much as possible that heat pump
could work up to -20C degrees of outside air. I think that subcooler could help to achieve this by evaporating all refrigerant liquid particles which didn't evaporate in the evaporator due to low outside temperature.

desA
03-09-2013, 05:00 PM
Your main problem may end up being the limiting high-side condensing temperature. Stretching the compression ratio on the low-pressure side (evap) will bring poor COP & high compressor exit temperatures.

Run tight TD's on evaporators & condensers.

Before cutting metal, run through Coolpack & see if it then makes sense.

frigolaki
04-03-2014, 11:14 AM
Hi samux
do you finish your project if you hawe news abot that it will be great pleasur to know how it working
is it working on -15
Kind Regards