Site News  |   Monitor Keywords  |   Monitor Archive  |   Organizer  |   Account Info  |

Economized vapor compression circuit

Economized vapor compression circuit description/claims

This application claims the benefit of U.S. Provisional Application No. 60/952,280, filed Jul. 27, 2007, which is hereby incorporated by reference.

The application generally relates to heating, ventilation, air conditioning and refrigeration (HVAC&R) systems.

Vapor compression refrigeration cycles typically require sub-cooling (i.e. cooling the refrigerant to a temperature lower than the saturation temperature at the condenser pressure) at the condenser outlet for stable operation of metering devices, such as expansion valves; sub-cooling also increases the refrigeration effect of refrigerant in the evaporator. Due to a low heat transfer coefficient of liquid refrigerants and small temperature differences between the refrigerant and the cooling fluid, the surface area of the condenser to achieve the desired level of sub-cooling can become considerable and a significant portion of the condenser surface can be dedicated to sub-cooling the refrigerant. Thus, the efficiency of the condenser, and in turn the entire system, is restricted.

Using a significant portion of the condenser surface for sub-cooling can have a negative impact on system efficiency, as surface area of the condenser that could be used for condensation is instead used for sub-cooling, resulting in a higher compressor discharge pressure being required.

More recent condenser coil technologies, such as multi-channel heat exchangers, operate at a lower condensing temperature, which reduces the temperature difference between the liquid refrigerant and air. This, in turn, increases the importance of sub-cooling in systems using such heat exchangers.

In other cases, liquid refrigerant may need to be piped over relatively long distances. As a result of the pressure drop across such distances, phase changes can occur at undesired locations, which may be avoided by first adequately subcooling the refrigerant.

Intended advantages of exemplary embodiments satisfy one or more of these needs or provide other advantageous features. Other features and advantages will be made apparent from the present specification. The teachings disclosed extend to those embodiments that fall within the scope of the claims, regardless of whether they accomplish one or more of the aforementioned needs.

One embodiment relates to an economized vapor compression circuit that includes an evaporator, a compressor, a condenser and an economizer. The evaporator, compressor, condenser and economizer are fluidly connected by a refrigerant line containing refrigerant, wherein liquid refrigerant leaving the economizer is split into a first stream and second stream. At a location intermediate the condenser and the evaporator, the first stream of refrigerant flows in a heat exchange relationship with refrigerant to be provided to the evaporator in which the first stream of liquid refrigerant expands and evaporates, subcooling refrigerant to be provided to the evaporator, the second stream of liquid refrigerant leaving the economizer flows to the evaporator.

In one exemplary embodiment, the economizer is a heat exchanger in which the sub-cooling also takes place. In another exemplary embodiment, the economizer is a flash tank and a separate sub-cooling heat exchanger is employed.

Another embodiment relates to a method for operating a vapor compression circuit that includes providing a refrigerant circuit having a condenser, an evaporator, an economizer, an expansion device, and a compressor fluidly connected by a refrigerant line containing refrigerant, directing substantially all refrigerant leaving the condenser to a first side of the economizer, diverting a minority portion of liquid refrigerant leaving the first side of the economizer to expand and enter a second side of the economizer to exchange heat with refrigerant in the first side of the economizer, and sub-cooling refrigerant in the first side of the economizer.

Still another embodiment relates to an economized vapor compression circuit that includes a compressor, a condenser, an economizer, an expansion device and an evaporator connected in a closed refrigeration loop. The economizer is configured to receive all refrigerant leaving the condenser and to provide sub-cooled liquid refrigerant to the evaporator. A portion of the liquid refrigerant leaving the economizer is diverted back to the economizer to exchange heat with the refrigerant entering the economizer from the condenser to sub-cool refrigerant being provided to the evaporator.

Certain advantages of some embodiments described herein include that by reducing or eliminating the need for sub-cooling at the condenser outlet permits the discharge pressure at the compressor to be lowered, resulting in better efficiency of the overall system. The size of the condenser surface may also be reduced so that the corresponding cost of the condenser is lowered.

In other embodiments, the sub-cooling may permit liquid refrigerant to be piped over longer distances.

Alternative exemplary embodiments relate to other features and combinations of features as may be generally recited in the claims.

• Provisional Patent
• Utility Patent

• What Is a Patent?
• What Is a Trademark or Servicemark?
• What Is a Copyright?
• Patent Laws