Enthalpy Increasing Buffer System
Have been pondering up something lately, maybe someone will have something to contribute.
A system wherein a compressor and condenser system is used as normal, however post condenser a suction line heat exchanger is added inline between the compressor and evaporator, and of course after the filter/drier mechanism. Past this suction line heat exchanger the system feeds into a capillary tube heading to the evaporator. However before this metering device a T is added and as well as a low temperature rated solenoid. (Post suction line heat exchanger after all). This solenoid feeds to a second even lower restriction metering device, upon which feeds to the suction line heat exchanger, such that this is turned in a sense into a subcooler.
The solenoid is linked to a fan cycler, and is set at the upper range of the systems high pressure; such that should a very high system pressure be reached, say 300 or 325 psi given the upcoming refrigerant information, the solenoid is opened feeding additional liquid refrigerant out of the high side, into the low side (raising low side pressure), and providing additional subcooling to the refrigerant mix.
The purpose of all of this being so that a system could be run using a near autocascade style mix, possible R290A and a double digit percentage of R170 (ethane). Thus the system operates at a lower temperature without wasting flow to maintain a sufficient heat exchanger temperature, and instead creates additional saturation when required.
Most likely the solenoid would be operated in short bursts, not greatly effecting the overall evaporator load, or when the system finds a nice equilibrium for a given load after first cooling down, does not find a need to operate the solenoid.
Any thoughts?
Re: Enthalpy Increasing Buffer System
Quote:
Originally Posted by
Reflexive
Have been pondering up something lately, maybe someone will have something to contribute.
A system wherein a compressor and condenser system is used as normal, however post condenser a suction line heat exchanger is added inline between the compressor and evaporator, and of course after the filter/drier mechanism. Past this suction line heat exchanger the system feeds into a capillary tube heading to the evaporator. However before this metering device a T is added and as well as a low temperature rated solenoid. (Post suction line heat exchanger after all). This solenoid feeds to a second even lower restriction metering device, upon which feeds to the suction line heat exchanger, such that this is turned in a sense into a subcooler.
The solenoid is linked to a fan cycler, and is set at the upper range of the systems high pressure; such that should a very high system pressure be reached, say 300 or 325 psi given the upcoming refrigerant information, the solenoid is opened feeding additional liquid refrigerant out of the high side, into the low side (raising low side pressure), and providing additional subcooling to the refrigerant mix.
The purpose of all of this being so that a system could be run using a near autocascade style mix, possible R290A and a double digit percentage of R170 (ethane). Thus the system operates at a lower temperature without wasting flow to maintain a sufficient heat exchanger temperature, and instead creates additional saturation when required.
Most likely the solenoid would be operated in short bursts, not greatly effecting the overall evaporator load, or when the system finds a nice equilibrium for a given load after first cooling down, does not find a need to operate the solenoid.
Any thoughts?
Somthing simmilar to what you describe is commenly used on multi temp packs and compound systems and is used to subcool the liquid below ambient temps or desuperheat the suction / discharge gases to / from the compressor. The only difference between what you have described and what is commenly used is, instead of capilaries, TEV's are used and plate heat exchangers. But the principle is the same, the reasons why it is used are different from your reasons though.
Cheers taz
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Re: Enthalpy Increasing Buffer System
The way I see it, your making a system that cannot start itself, but can maintain itself once it reaches equilibrium. Or at least the conditions to reach equilibrium are not what you'd like to encounter.
Re: Enthalpy Increasing Buffer System
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When you two stage a refrigerant you add extra superheat during the compression cycle, so to reduce the superheat some form of de-superheating needs to take place.
So you are right in saying that "a system that cannot start itself, but can maintain itself once it reaches equilibrium", sort of.
Think why you would need to subcool the liquid below ambient and think why you would need to de-superheat the compressor gases to ensure the system works efficiently?
Straight forward systems need no extra help to work efficiently, but complex systems need extra subcooling and de-superheating in place to increase the overall efficiently, but at a cost. To increase the efficiently there is a cost involved and that cost comes in the way of extra energy used to de-superheat or subcool, but the costs should be outweighd by the benifits.
taz
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