- #1
Low-Q
Gold Member
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- 9
I have been looking at the basic operation of a heat pump. On these pumps there is an expansion valve. This valve is a narrow hole where the condensed working fluid is passing through, then evaporation happens in the low pressure side - after this hole.
I assume this valve act as a resistance, and therfor I assume it also result in loss of energy.
Would it be better to use an inverted pump to do the same job instead?
I have been thinking of something similar to the motor in pneumatic tools - but instead this will be a hydraulic driven motor as the condensed working fluid is liquid. So using this kind of motor as a replacement of the expansion valve, the liquid pass through this motor, and the motor will start to rotate. This motor is some how mechanically connected to the pump, so the pump will require little less input to compress the working fluid (?)
I understand that this new expansion valve (motor) must restrict the flow in order to maintain the different compression rate in the two sides, and therfor have less "pump capacity" than the pump. But it would not cause as much loss as a traditional expansion valve will do. Or what?
The compression difference between the two sides I have read is about 1 to 5 at normal operation. However, this relationship will depend on the outside temperature and the wanted inside temperature, and the type of heat pump. So if I look at an ideal heat pump, the efficiency will increase with about 20% or so with the alternative expansion valve.
Do this reasoning looks rational?
Vidar
I assume this valve act as a resistance, and therfor I assume it also result in loss of energy.
Would it be better to use an inverted pump to do the same job instead?
I have been thinking of something similar to the motor in pneumatic tools - but instead this will be a hydraulic driven motor as the condensed working fluid is liquid. So using this kind of motor as a replacement of the expansion valve, the liquid pass through this motor, and the motor will start to rotate. This motor is some how mechanically connected to the pump, so the pump will require little less input to compress the working fluid (?)
I understand that this new expansion valve (motor) must restrict the flow in order to maintain the different compression rate in the two sides, and therfor have less "pump capacity" than the pump. But it would not cause as much loss as a traditional expansion valve will do. Or what?
The compression difference between the two sides I have read is about 1 to 5 at normal operation. However, this relationship will depend on the outside temperature and the wanted inside temperature, and the type of heat pump. So if I look at an ideal heat pump, the efficiency will increase with about 20% or so with the alternative expansion valve.
Do this reasoning looks rational?
Vidar