Heat Pump Component Design Efficiency

[rimmer]

I am interested in the inherent efficiency and performance limitations of various Heat Pump components.

I'll start a sub thread for specific components.

rimmer

[rimmer]

Do you know of any specific losses or efficiency issues associated with current heat pump expansion valves? Are friction losses noticeable?

[mad fridgie]

An expansion valve, is device that restricts flow, so by definiation, friction is noticable.

[rimmer]

Are there any figures quoted for this friction loss in a vapour compression heat pump?
Any other efficiency issues, say, due to loss of suction?

[mad fridgie]

Are there any figures quoted for this friction loss in a vapour compression heat pump?
Any other efficiency issues, say, due to loss of suction?

A heat pump in principle is no different to refrigeration, a huge amount info is available on refrigeration principles, start with the basics. You have to master this before you starting looking into specifics.

[rimmer]

A heat pump in principle is no different to refrigeration, a huge amount info is available on refrigeration principles, start with the basics. You have to master this before you starting looking into specifics.

I'm familiar with the basic principles: I'm trying to understand the various causes of energy loss through out the system. Some causes are better documented than others.

rimmer

[mad fridgie]

I'm familiar with the basic principles: I'm trying to understand the various causes of energy loss through out the system. Some causes are better documented than others.

rimmer

being familar is not quite the same as master the basic principles. If you master them , you will find that most of your answers to your future questions, become apparent.
So lets have a look at the suction line ( a question asked) I will ask you questions to aid better understanding (general applications)
Is it hot or cold?
Is energy absorbed or rejected? (is this useful or not?)
Whats happens to the pressure down the length?
What effect do the above have on density.
Does this have an inffluence on the compressor?, if yes/no why?

[Brian_UK]

Are there any figures quoted for this friction loss in a vapour compression heat pump?
Any other efficiency issues, say, due to loss of suction?

Means compressor is broken, somewhat inefficient.

[desA]

Do you know of any specific losses or efficiency issues associated with current heat pump expansion valves? Are friction losses noticeable?

As MF mentoned, by their very nature, they should be. If not, then I'd begin looking for a new TXV supplier.

[desA]

@rimmer:

Perhaps you could start by telling us more about yourself, & your interest in heat-pumps?

[mad fridgie]

Means compressor is broken, somewhat inefficient.

Well I missed that one!!!! LOL

[rimmer]

I am an MSc student writing a paper on user control of heat pumps.

As part of my context, I am describing theoretical limits to COP due to Carnot and the P-H characteristics of the refrigerant. I am also looking at mechanical and electrical losses as well as system inefficiencies due to intermittent control.

This post is trying to pick up on some of the 'in the field' knowledge that you HVAC guys may have in this area.

rimmer

[mad fridgie]

I am an MSc student writing a paper on user control of heat pumps.

As part of my context, I am describing theoretical limits to COP due to Carnot and the P-H characteristics of the refrigerant. I am also looking at mechanical and electrical losses as well as system inefficiencies due to intermittent control.

This post is trying to pick up on some of the 'in the field' knowledge that you HVAC guys may have in this area.

rimmer

I will point you in a direction, look at electrical energy in, not KWs but KVA (power factor) this has a large influence on power supply systems, this is specific to components.
I presume you are talking air to air heat pumps, you then need to look what comfort levels effecting (Ie hot or cold start for fans)
Then you need to look at location of equipment and effects of stratification in relation to comfort level (cold feet syndrome)

[rimmer]

No, Not air source. Ground or Water Source

[rimmer]

...... and hydronic underfloor heating. However, the build environment and thermal comfort is not the subject of this post

[mad fridgie]

Is thermal comfort the goal, so then has to be the starting point, if not then, any theory is flawed. This must affect the intermittent, control. Is this not what you are asking?
Are you not in effect trying to balance losses verses gains during a cycling system (energy mass balance)
the carnot cycle is well proven, so not quite sure what you are trying achieve.
maybe you can ask specific questions.