liquid storage and suction accumulator

[Lc_shi]

HI sirs
I've designed a heat pump system and use a suction accumulator to accommodate the winter operation. If it's necessary to add a liquid storage for the capacity variables? pls advise.

regards
LC

[lraja]

If your heat pump is one with small amount of refrigerant charge, perhaps you could use a suction line accumulator to handle the variation in charge requirement in switching between heating/cooling modes. But this is so only if you use a 4-way reversing valve to switch condenser and evaporator to suit demand (cooling or heating). Other switching methods may not have this issue.

However, if the internal volumes of the condenser and evaporator differ very much, you are going to need extra storage capacity during at least one mode of operation, may be during heating/ or cooling depending on the system design, passive volume within the system and the amount of charge


raja

[taz24]

HI sirs
I've designed a heat pump system and use a suction accumulator to accommodate the winter operation. If it's necessary to add a liquid storage for the capacity variables? pls advise.

regards
LC


What type of metering device does it have? I would use a liquid reciever if it has a thermostatic expansion device to allow for the verible demand.

Cheers taz.

[Lc_shi]

Hi Sir
How do u think if the suction line accumulator to take the task ? heating mode's refrigerant mass flow is about 50% of cooling mode,if the accumulator can store the extra refrigerant ,is it all right?

thanks
LC

[taz24]

Hi Sir
How do u think if the suction line accumulator to take the task ? heating mode's refrigerant mass flow is about 50% of cooling mode,if the accumulator can store the extra refrigerant ,is it all right?

thanks
LC


In principle it could work but I personaly do not like the idea of using the suction as a storage area. I prefer to have all my excess refrigerant in liquid form and in the receiver.

Cheers taz.

[taz24]

Hi Sir
How do u think if the suction line accumulator to take the task ? heating mode's refrigerant mass flow is about 50% of cooling mode,if the accumulator can store the extra refrigerant ,is it all right?

thanks
LC

What you must bear in mind is the compressor is no more than a glorified suction pump. It will suck as much gas as it can possible get within the constrainst you set it, ie speed, bore, stroke, and effiency. So you cannot store refrigerant in the suction with out affecting the operating parameters of the system.

cheers taz.

[star882]

But this is so only if you use a 4-way reversing valve to switch condenser and evaporator to suit demand (cooling or heating). Other switching methods may not have this issue.
What methods besides reversing valves are used in bidirectional heat pumps? Every heat pump I know of uses a reversing valve.

[lraja]

What methods besides reversing valves are used in bidirectional heat pumps? Every heat pump I know of uses a reversing valve.


Heat pupms do not have to be bidirectional always. Switching the heat transfer fuid (feeding the application) between the evaporator and condenser to obtain heating/cooling goes well with single direction systems. I do not have examples to post, but this method has been researched, and found better suited for refrigerant mixtures

[taz24]

Heat pupms do not have to be bidirectional always. Switching the heat transfer fuid (feeding the application) between the evaporator and condenser to obtain heating/cooling goes well with single direction systems. I do not have examples to post, but this method has been researched, and found better suited for refrigerant mixtures

But what is the device that actualy switches direction?:confused:
somthing has to change the flow from one way to the other.

Cheers taz.

[Peter_1]

The excess refrigerant can also be stored at low load conditions in the condenser, a technique used in many chillers (Climaveneta, Carrier, Rhoss, Clivet, Ciat,..)
At low load, you then have at the same time an oversized condenser, so capable of storing refrigerant and even subcool it.

[taz24]

At low load, you then have at the same time an oversized condenser, so capable of storing refrigerant and even subcool it.


I agree the oversized cond when in low load conditions stores liquid but more benificial to the system when in high load conditions the oversized cond will be capable of working better.

Cheers taz.