Patent Application
20240263850
This application claims priority from and incorporates by reference European Patent Application 23 154 664.9 filed on Feb. 2, 2023.
The invention relates to a sorption heat pump. The invention furthermore relates to a sorption cycle performed by the sorption heat pump.
Sorption heat pumps and sorption cycles are well known for building applications and operate in a reverse cycle mode or by hot gas defrosting during defrost operation.
The known methods do not generate any usable heat during defrosting. Intermittent operation of the compressors and abrupt change of the pressures during switching between normal and defrost operation load and wear the components of known sorption heat pumps.
It is an object of the invention to improve efficiency during defrosting and to reduce wear. Improving upon known sorption heat pumps the object is achieved by a sorption heat pump including a gaseous refrigerant and a liquid solvent; a diluted solution and a concentrated solution, wherein the diluted solution and the concentrated solution are single phase mixes of the solvent and the refrigerant; an absorber in which the diluted solution absorbs the refrigerant at a high-pressure level and emits a first heat; and a cooling device including plural cooling registers, each respective cooling register including a respective air cooler and a respective expansion valve in which the concentrated solution is expanded to a low-pressure level during normal operation of the respective cooling register so that the concentrated solution absorbs a second heat from ambient air in the respective air cooler and expels the refrigerant, wherein each respective air cooler is defrostable individually by supplying a third heat to the respective air cooler in a defrost operation of the respective air cooler that interrupts the normal operation of the respective air cooler, wherein the cooling device includes a bypass that runs a partial flow of the concentrated solution through the respective cooling register at the high-pressure level during the defrost operation of the respective cooling register so that the partial flow of the concentrated solution emits the third heat.
The object is also achieved by a sorption cycle including a gaseous refrigerant and a liquid solvent; a diluted solution and a concentrated solution, wherein the diluted solution and the concentrated solution are single phase mixes of the solvent and the refrigerant; wherein the diluted solution absorbs the refrigerant and emits a first heat at a high-pressure level, wherein the concentrated solution is expanded to a low-pressure level during normal operation in plural cooling registers, each respective cooling register including a respective air cooler, so that the concentrated solution absorbs a second heat from ambient air in the respective air cooler and thereby expels the refrigerant, wherein the respective air cooler is defrosted by supplying a third heat to the respective air cooler in a defrost operation of the respective air cooler that interrupts the normal operation of the respective air cooler, wherein a respective partial flow of the concentrated solution emits the third heat at the high-pressure level during the defrost operation in the respective air cooler.
It is proposed according to the invention that the cooling device includes a bypass, which runs a partial flow of the concentrated solution at the high-pressure level through one of the cooling registers during defrost operation of the one of the cooling registers, so that the partial flow of the concentrated solution emits the heat. The sorption heat pump according to the invention uses excess heat for defrosting which would otherwise have to be actively extracted from the diluted solution and thus increases efficiency. A mass flow in the thermodynamic cycle is reduced by a portion during defrosting wherein the portion absorbs heat in the defrosting cooling register during normal operation. This accordingly reduces the heating power of the sorption heat pump according to the invention during defrosting. The pressures in the cycle, however, remain unchanged which significantly reduces loading and wear of the components.
The concentrated solution expels the refrigerant in a sorption heat pump according to the invention between the cooling registers and the absorber at the low-pressure level and the remaining diluted solution is raised to the high-pressure level by a pump and the refrigerant is raised to the high-pressure level by a compressor.
Advantageously, the partial flow is fed back into the concentrated solution in a sorption heat pump according to the invention after putting out the defrost heat. This completes the cycle during defrost operations. Advantageously the partial flow is run through a respective check valve in parallel to the expansion valve of the respective cooling register. The concentrated solution then flows in opposite directions through the air cooler during normal operation and defrost operation. The expansion valve and the check valve can be configured in a space saving manner in one component as an expansion check valve.
Advantageously, the cooling device in a sorption heat pump according to the invention includes cut off valves which alternatively run the concentrated solution from the air cooler to the absorber during normal operation of one of the cooling registers or run the concentrated solution from the bypass to the air cooler during defrost operation. Actuating the cut off valves switches the respective cooling register between normal operation and defrost operation. The cut off valves of a cooling register can be configured in a space saving manner in one component as a 3/2-way valve.
Advantageously the cooling device in a sorption heat pump according to the invention includes a control valve which controls a residual flow of the concentrated solution parallel to the bypass. The control valve compensates the pressure loss of the partial flow in the bypass and in the air cooler. Alternatively the partial flow can include an entirety of the concentrated solution when there is no residual flow. Then, the cooling register running in defrost operation is defrosted with maximum power, thus as quickly as possible.
Advantageously, the solvent in the sorption heat pump according to the invention is water and the refrigerant is ammonia. Water and ammonia are natural substances and well proven in refrigeration applications.
Improving upon the known sorption cycles it is proposed according to the invention that a respective partial flow of the concentrated solution emits the defrost heat in the air cooler at the high-pressure level. This process is performed by a sorption heat pump according to the invention and is characterized by the same advantages.
Advantageously, the concentrated solution runs through each of the air coolers in opposite directions during normal operations and during defrost operations in a sorption cycle according to the invention. Reversing the flow direction in the existing conduits facilitates minimizing the required bypass conduits.
The invention is subsequently described based on an embodiment with reference on a drawing FIGURE showing a schematic of a sorption heat pump.
The sorption heat pump 1 according to the invention shown in the drawing FIGURE includes an absorber 2, a cooling device 3, a separator 4, a compressor 5, a pump 6 and conduits 7. The conduits 7 connect the absorber 2, the cooling device 3 and the separator 4 in this sequence to form a closed loop system, wherein the compressor 5 is arranged in a refrigerant path 8 and the pump 6 is arranged in a solvent path 9 running parallel to the refrigerant path 8 so that the separator 4 is connected with the absorber 2. The conduit 7 between the absorber 2 and the cooling device 3 and the solvent path 9 run through a solution heat exchanger 10.
The cooling device 3 includes two cooling registers 11 arranged in parallel. Starting at the absorber 2 and moving to the separator 4 each cooling register 11 includes an expansion valve 12 and a check valve 13 arranged in parallel to the expansion valve, an air cooler 14 and a first check valve 15. The air coolers 14 are connectable with a bypass 17 through a second cut off valve 16 respectively arranged parallel to the first cut off valve 15, wherein the bypass 17 branches off upstream of the expansion valves 12. The cooling device 3 includes a control valve 19 between the branch off 18 of the bypass 17 and the expansion valves 12.
The cut off valves 15, 16 are configured to switch the cooling registers 11 respectively into normal operation or defrost operation.
In the sorption cycle according to the invention using ammonia (NH3) as a refrigerant and water as a solvent, a flow of the diluted solution absorbs a flow of the refrigerant in the absorber 2 and transfers heat to a heating medium.
When both cooling registers 11 are run in normal operating mode the concentrated solution exiting the absorber 2 at a high pressure of 27 bar at a flow rate of 1.39 kg/s is evenly distributed between both cooling registers 11, expanded in both expansion valves 12 to an identical low pressure so that the concentrated solution cools down and is then heated in both air coolers 14. The concentrated solution heated in the two air coolers 14 is combined through the open first cut off valves 15 in the subsequent separator 4 and expels the refrigerant in a gaseous form. The remaining diluted solution is raised back to the high pressure in the solvent path 9 by the pump 6, and the gaseous refrigerant is raised back to high pressure in the refrigerant path 8 by the compressor 5 and fed into the absorber 2. The diluted solution absorbs the refrigerant again in the absorber 2, is cooled down and transfers heat to a heating medium.
Known non-illustrated lamella of the air cooler 14 frost over during normal operation. The cooling registers 11 are switched from normal operation to defrost operation in the sorption cycle according to the invention in an alternating pattern in order to be defrosted.
In order to defrost the first cooling register 11, the control valve 19 is closed and the first cut off valve 15 in the first cooling register 11 is closed and the second cut off valve 16 is opened. A partial flow that includes an entirety of the concentrated solution runs through the second cut off valve 16 at 30 degrees C. at high pressure into the air cooler 14 of the first cooling register 11, heats the first air cooler 14 and ambient air with a defrosting power of 138 KW, exits the first air cooler 14 at 10° C. and flows through the check valve 13 into the second cooling register 11 that continues to run in normal operation.
The concentrated solution is expanded to a low pressure of 2.2 bar by the expansion valve 12 in the second cooling register 11, cools down to −10° C. in the process and absorbs 785 KW in the air cooler 14 from the ambient air and exits the cooling device 3 at −5° C. through the open first cut off valve 15.
The concentrated solution expels 0.67 kg/sec gaseous refrigerant in the separator 4 and the refrigerant is compressed to the high pressure in the compressor 5 with 365 kW. The remaining 0.72 kg/sec diluted solution are fed by the pump 6 to the absorber 2 by 5 KW and thus heated to 66° C. in the solution heat exchanger 10.
When the first cooling register 11 is defrosted completely, it is switched back to normal operation by switching the control valve 19, the first cut off valve 15 and the second cut off valve 16.
The control valve 19 alternatively facilitates to only run an actual partial flow of the concentrated solution into the cooling register 11 in defrost operation. This reduces defrosting power and increases time required for defrosting.
| Number | Date | Country | Kind |
|---|---|---|---|
| EP23154664.9 | Feb 2023 | EP | regional |
