High-efficiency cooling systems and methods for a computer data center using refrigerant recirculation
View Patent ↗To facilitate the use of high-efficiency heat exchangers in a computer data center, a refrigerant recirculation line is provided to direct at least some refrigerant from the first refrigerant outlet of the first heat exchanger through an in-line refrigerant pump to mix with the refrigerant from the refrigerant supply and then flow to the first refrigerant inlet of the first heat exchanger. At least partial recirculation of refrigerant facilitates the use of warmer inlet refrigerant while still providing sufficient heat extraction.
1 . A cooling system for a facility employing equipment requiring active cooling, the cooling system comprising:
a refrigerant supply line providing a refrigerant at a first pressure from a refrigerant source,
a refrigerant return line directing the refrigerant at a second pressure toward the refrigerant source for cooling and recirculating of the refrigerant at the refrigerant source, wherein the second pressure is lower than the first pressure,
a first heat exchanger configured to use the refrigerant circulating through the first heat exchanger to cool air or liquid which passes through the first heat exchanger and is used for active cooling of the equipment in the facility, the first heat exchanger having a first refrigerant inlet configured to receive at least some refrigerant from the refrigerant supply line, the first heat exchanger having a first refrigerant outlet operably connected to direct at least some refrigerant to the refrigerant return line, and
a first recirculation line configured to direct at least some refrigerant from the first refrigerant outlet of the first heat exchanger through an in-line refrigerant pump to mix with the refrigerant from the refrigerant supply line and then flow to the first refrigerant inlet of the first heat exchanger,
wherein the in-line refrigerant pump is configured to increase refrigerant pressure from the second pressure to the first pressure, and wherein the in-line refrigerant pump is configured to provide flow only to refrigerant in the first recirculation line and not to any other refrigerant in the cooling system,
wherein the in-line refrigerant pump is configured not to provide refrigerant flow to the refrigerant source,
thereby increasing the heat exchanging efficiency of the first heat exchanger by recirculating at least some refrigerant flowing through the first heat exchanger.
2 . The cooling system of claim 1 , further comprising at least one temperature sensor configured to measure refrigerant temperature at the first refrigerant inlet of the first heat exchanger and/or at the first refrigerant outlet of the first heat exchanger.
3 . The cooling system of claim 1 , further comprising at least one additional heat exchanger, wherein the first recirculation line is configured to direct at least some refrigerant from the first refrigerant outlet of the first heat exchanger or from a refrigerant outlet of the at least one additional heat exchanger through the in-line refrigerant pump to flow to the first refrigerant inlet of the first heat exchanger.
4 . The cooling system of claim 1 , further comprising a return line temperature sensor positioned in the refrigerant return line downstream of the first heat exchanger, wherein the return line temperature sensor is configured to measure refrigerant temperature in the refrigerant return line prior to reaching the refrigerant source.
5 . The cooling system of claim 1 , wherein the refrigerant and/or the liquid passing through the first heat exchanger is selected from a group consisting of a one-phase refrigerant, a two-phase refrigerant, water, and a mix of water and glycol.
6 . The cooling system of claim 1 , wherein the facility is a computer data center and the air or liquid passing through the first heat exchanger is used for active cooling of computer equipment of the data center.
7 . The cooling system of claim 1 , wherein the cooling system further comprises a refrigerant circulation loop comprising the first heat exchanger and a supplemental heat exchanger positioned downstream of the first heat exchanger, the supplemental heat exchanger is placed outside the facility.
8 . The cooling system of claim 7 , further comprising a circulation bypass line with an in-line circulation bypass valve, the circulation bypass line configured to direct the refrigerant directly downstream and not through the supplemental heat exchanger when an ambient temperature is at or above a refrigerant temperature at the first refrigerant outlet of the first heat exchanger.
9 . A method for cooling a facility employing equipment requiring active cooling, the method comprising the following steps:
a. directing a refrigerant from a refrigerant supply line pressurized at a first pressure through a first heat exchanger, wherein the first heat exchanger is configured to use the refrigerant circulating through the first heat exchanger to cool air or liquid which passes through the first heat exchanger and is used for active cooling of the equipment in the facility,
b. directing the refrigerant to flow from the first heat exchanger to a refrigerant return line at a second pressure, wherein the second pressure is lower than the first pressure, and
c. using an in-line refrigerant pump that provides flow only to refrigerant in a first recirculation line and not to the refrigerant source or any other refrigerant in the cooling system, and that is configured not to provide refrigerant flow to the refrigerant source, directing at least some refrigerant after passing through the first heat exchanger to mix with the refrigerant from the refrigerant supply line and then flow again through the first heat exchanger, wherein the in-line refrigerant pump increases refrigerant pressure from the second pressure to the first pressure, thereby recirculating at least some refrigerant to flow through the first heat exchanger to increase heat extraction therefrom.
10 . The method of claim 9 , wherein the facility is a computer data center and the air or liquid passing through the first heat exchanger is used for active cooling of computer equipment of the data center.
11 . The method of claim 9 , further comprising a step of providing a supplemental heat exchanger positioned outside the facility, and directing refrigerant from the first heat exchanger to the supplemental heat exchanger only when an ambient temperature is below a refrigerant temperature at the first refrigerant outlet of the first heat exchanger to at least partially extract heat from the refrigerant prior to directing the refrigerant to the refrigerant return line.
12 . The method of claim 11 , further comprising a step of bypassing the supplemental heat exchanger and directing the refrigerant directly to the refrigerant return line when the ambient temperature is at or above the refrigerant temperature at the first refrigerant outlet of the first heat exchanger.
13 . The method of claim 9 , further comprising a step of directing at least some refrigerant after passing through the first heat exchanger to flow through at least one additional heat exchanger prior to directing the refrigerant to the refrigerant return line.