Refrigeration – Refrigeration producer – With lubricant handling means
Reexamination Certificate
2001-02-08
2003-05-06
Doerrler, William C. (Department: 3743)
Refrigeration
Refrigeration producer
With lubricant handling means
C062S084000, C062S503000, C165S110000
Reexamination Certificate
active
06557371
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to apparatus and methods for discharging fluids. More particularly, the present invention relates to an apparatus and associated method for discharging, from an outlet chamber of a heat exchanger, a fluid and a liquid separated from the fluid.
Air-conditioning, refrigeration, or heat-pump systems typically include a compressor, two heat exchangers, and an expansion valve. These components are connected by a series of tubes and pipes to form a circuit through which a fluid flows for cooling or heating a space or a heat transfer fluid. Typically the fluid undergoes a phase change while flowing through the heat exchangers. In one of the heat exchangers conventionally called a condenser, at least a portion of the fluid undergoes a phase change from vapor to liquid, and thereby loses its heat content. In the other heat exchanger conventionally called an evaporator, at least a portion of the fluid undergoes a phase change from liquid to vapor, and thereby increases its heat content. Thus, in an air-conditioning or refrigeration system, a space or a heat transfer fluid to be cooled is coupled with the evaporator. In a heat-pump system, on the other hand, a space or a heat transfer fluid to be heated is coupled with the condenser. Also, a single system may serve as both an air-conditioning or refrigeration system and a heat-pump system by reversing the flow of the fluid.
The fluid in air-conditioning, refrigeration, or heat-pump systems enters the evaporator in the form of a subcooled liquid, a saturated liquid, or a mixture of liquid and vapor. While the fluid flows through the evaporator in small metal tubes, it absorbs heat from a space or a heat transfer fluid and at least part of the liquid portion becomes vapor. Thus, depending on the amount of heat absorbed by the fluid, the fluid exits the evaporator in the form of a mixture of liquid and vapor, a saturated vapor, or a superheated vapor. The fluid then flows through the compressor to increase its pressure. Subsequently, the fluid flows through the condenser where it loses heat to another space or another heat transfer fluid. Depending on the amount of heat lost by the fluid, the fluid exits the condenser in the form of a subcooled liquid, a saturated liquid, or a mixture of liquid and vapor. While the fluid exiting the evaporator or the condenser may assume different forms, at least a portion of the fluid undergoes a phase change due to either heat loss or heat absorption.
Certain air-conditioning, refrigeration, or heat-pump systems are designed such that the fluid exiting the evaporator contains a mixture of liquid and vapor. For example, because the heat transfer characteristic of the fluid is typically poor if more than 90% of the fluid is vapor, an evaporator in a certain air-conditioning or refrigeration system is designed to produce a fluid that contains about 90% vapor portion and 10% liquid portion at its outlet chamber. This evaporator may achieve the maximum heat removal from a space or other heat transfer fluid to be cooled. Part of the liquid portion in the fluid, however, fails to exit the evaporator directly with a bulk flow because it tends to separate from the bulk flow and collects at the bottom portion of the outlet chamber due to gravity. For example, as much as 75% of the liquid portion may separate from the bulk flow and fall to the bottom of the outlet chamber. This separated liquid collecting in the outlet chamber poses at least three problems.
First, the separated liquid may eventually damage the compressor. As the separated liquid continues to build up in the outlet chamber, the liquid level approaches an outlet opening. The liquid then tends to flow out suddenly in a large volume through the outlet opening. This phenomenon is commonly referred to as a liquid “slug.” During ongoing operations, the liquid collected in the outlet chamber continues this pattern of build up and sudden “slug” removal rather than a steady and continuous removal. This pattern, referred to as a cyclical purging, may eventually decrease a compressor life. Although compressors may endure a steady and continuous influx of liquid in small amount, they are typically not designed to bear cyclical influxes of large liquid “slugs.”
Second, the separated liquid may hinder the flow of the fluid through the evaporator. As the liquid builds up, it blocks some of the metal tubes through which the fluid discharges to the outlet chamber. This blockage impedes a steady flow of the fluid and may decrease the efficiency of the overall air-conditioning, refrigeration, or heat-pump system.
Third, the separated liquid may deprive needed liquids to other components of the air-conditioning, refrigeration, or heat-pump system. For example, in some applications, the fluid includes a small amount of oil to ensure smooth mechanical operation of the compressor. This oil typically falls with the separated liquid to the bottom of the outlet chamber. Without a continuous, steady removal of the separated liquid from the outlet chamber, the oil needed for a proper mechanical operation may not reach the compressor.
Therefore, there exists a need for an apparatus and method for continuously and steadily discharging a liquid, which is separated from the bulk flow of a fluid and collected in an outlet chamber.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to an apparatus and associated method for discharging, from an outlet chamber of a heat exchanger, a fluid and a liquid separated from the fluid that obviate one or more of the limitations and disadvantages of prior art apparatus and methods. The advantages and purposes of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The advantages and purposes of the invention will be realized and attained by the elements and combinations particularly pointed out in the appended claims.
To attain the advantages and in accordance with the purposes of the invention, as embodied and broadly described herein, the invention is directed to an apparatus for discharging from an outlet chamber a fluid and a liquid separated from the fluid. The outlet chamber is configured to collect the separated liquid. The outlet chamber is in fluid communication with an outlet opening disposed on an exit surface of the outlet chamber. The apparatus includes a plate positionable in the outlet chamber adjacent to the exit surface to form a channel between the plate and the exit surface. The plate is configured to protrude over the outlet opening so that the fluid flowing through the outlet chamber and into the outlet opening pulls the liquid collected in the outlet chamber through the channel and out through the outlet opening with the fluid.
In another aspect, the invention is directed to a method for discharging from an outlet chamber a fluid and a liquid separated from the fluid. The outlet chamber is configured to collect separated liquid. The outlet chamber is in fluid communication with an outlet opening disposed on an exit surface of the outlet chamber. The method steps includes: positioning a plate in the outlet chamber adjacent to the exit surface so that the plate and the exit surface form a channel therebetween and the plate protrudes over the outlet opening; and flowing the fluid through the outlet chamber and into the outlet opening to pull the liquid collected in the outlet chamber through the channel and out through the outlet opening with the fluid.
In yet another aspect, the invention is directed to a heat exchanger. The heat exchanger includes a main chamber, an outlet chamber, an outlet opening, and a plate. A fluid flows through the main chamber to absorb heat. The outlet chamber is configured to receive the fluid from the main chamber and to collect a liquid separated from the fluid. The outlet opening is disposed on an exit surface of the outlet chamber and is in fluid communication with the outlet chamber. The
Doerrler William C.
Maria Carmen Santa
McNees Wallace & Nurick
Sattizahn Brian T.
York International Corporation
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