The present disclosure relates to refrigeration. More particularly, it relates to refrigerant separators.
Earlier proposals for ejector refrigeration systems are found in U.S. Pat. No. 1,836,318 and U.S. Pat. No. 3,277,660.
In the normal mode of operation, gaseous refrigerant is drawn by the compressor 22 through the suction line 56 and inlet 24 and compressed and discharged from the discharge port 26 into the discharge line 28. In the heat rejection heat exchanger, the refrigerant loses/rejects heat to a heat transfer fluid (e.g., fan-forced air or water or other fluid). Cooled refrigerant exits the heat rejection heat exchanger via the outlet 34 and enters the ejector primary inlet 40 via the line 36.
The exemplary ejector 38 (
Use of an ejector serves to recover pressure/work. Work recovered from the expansion process is used to compress the gaseous refrigerant prior to entering the compressor. Accordingly, the pressure ratio of the compressor (and thus the power consumption) may be reduced for a given desired evaporator pressure. The quality of refrigerant entering the evaporator may also be reduced. Thus, the refrigeration effect per unit mass flow may be increased (relative to the non-ejector system). The distribution of fluid entering the evaporator is improved (thereby improving evaporator performance). Because the evaporator does not directly feed the compressor, the evaporator is not required to produce superheated refrigerant outflow. The use of an ejector cycle may thus allow reduction or elimination of the superheated zone of the evaporator. This may allow the evaporator to operate in a two-phase state which provides a higher heat transfer performance (e.g., facilitating reduction in the evaporator size for a given capability).
The exemplary ejector may be a fixed geometry ejector or may be a controllable ejector.
Various modifications of such ejector systems have been proposed. One example in US20070028630 involves placing a second evaporator along the line 46. US20040123624 discloses a system having two ejector/evaporator pairs. Another two-evaporator, single-ejector system is shown in US20080196446.
One aspect of the disclosure involves a system having a compressor. A heat rejection heat exchanger is coupled to the compressor to receive refrigerant compressed by the compressor. The system has a heat absorption heat exchanger. The system includes a separator comprising a vessel having an interior. The separator has: an inlet; a first outlet; and a second outlet. An inlet conduit may extend from the inlet and may have the conduit outlet positioned to discharge an inlet flow into the vessel interior to cause the inlet flow to hit a wall before passing to a liquid refrigerant accumulation in the vessel.
In various implementations, an ejector may have: a primary inlet coupled to the heat rejection heat exchanger to receive refrigerant: a secondary inlet; and an outlet. The separator inlet may be coupled to an outlet of the ejector. An expansion device may be immediately upstream of the heat absorption heat exchanger. The refrigerant may comprise at least 50% carbon dioxide, by weight. The separator may also be used as a flash tank device for an economized cycle.
Other aspects of the disclosure involve methods for operating the system.
The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims.
Like reference numbers and designations in the various drawings indicate like elements.
The separator 48 of
Nevertheless, it may be desirable to provide a controlled amount of mixed phase outlet flow (e.g., a slight amount of vapor discharged through the liquid outlet and/or a slight amount of liquid discharged through the vapor or gas outlet). Means for providing such mixed phase flow may also be provided if desired. For example, by feeding a two-phase mixture into the compressor, the discharge temperature of the compressor can be reduced if desired (thus extending the compressor system operating range). Feeding a suction line heat exchanger (SLHX) and/or compressor with small amount liquid are also expected to improve both SLHX and compressor efficiency. Exemplary refrigerant is delivered as 85-99% quality (vapor mass flow percentage), more narrowly, 90-98% or 94-98%. Also by feeding a two-phase mixture to the expansion valve upstream of the evaporator one can precisely control the system capacity, which can prevent unnecessary system shutdowns (comfort and improved reliability) and improve temperature control. This may help improve refrigerant distribution in the evaporator manifold and further improve evaporator performance Exemplary refrigerant is delivered as 1-10% quality (vapor mass flow percentage), more narrowly 2-6%.
The exemplary separator 170 (
A lower end 186 of the tube insert 185 is closed and sits on the bottom 187 of the vessel (e.g., for support so as to minimize stress on the joint with the inlet conduit 182). Along an intermediate portion (still above a surface of the accumulation 200) the tube insert 185 bears apertures (holes) 188. The apertures 188 deflect the inlet flow 120 to reduce the velocity with which the inlet flow encounters the accumulation. For example, the apertures 188 may cause the inlet flow to deflect off the inner surface of the sidewall 189 of the vessel (e.g., flow down the sidewall to the accumulation). This deflection reduces foaming in the accumulation 200 and helps provide controlled balances of vapor and liquid in the flows 177 and 179.
In one exemplary implementation, the inlet tube has an inner diameter (ID) of 15.9 mm which corresponds to a particular standard tube size. Other sizes may be used depending upon system requirements.
In the example, the holes 188 are grouped in two rows of five holes with each hole of one group diametrically opposite an associated hole of the other group. The exemplary holes are 0.25 inch (6.35 mm) in diameter. Other patterns of holes may be provided. For example, the patterns may be provided to create specific flow patterns, to accommodate other internal components, or the like. Similarly, hole orientation may be varied off radial or off horizontal. For example, angling of the holes upward at angles of up to 45° off horizontal/radial may allow the flows along the sidewall to use more of the sidewall. More broadly, an exemplary tube size for the inlet conduit or an insert therein is one eighth of an inch to two inches (3.2 mm-50.8 mm). Similarly, an exemplary range of hole sizes (especially for drilled holes) is 0.8 mm-20 mm in diameter depending upon the desired flow rate, conduit size, etc. Non-circular holes may have similar exemplary cross-sectional areas. An exemplary ratio of total hole area to local tube internal cross-sectional area is 0.5-20, more narrowly 1-5 or 1-2.
The exemplary first outlet 176 is at the downstream end of a U-tube (or J-tube) 190. The U-tube extends to a second end (gas inlet end) 192 open to the headspace 194 of the tank for drawing a flow 196 of gas from the headspace. A lower portion (trough or base) 198 of the U-tube is immersed in the liquid refrigerant accumulation 200 in a lower portion of the tank, below the headspace. To entrain the desired amount of liquid 202 into the gas flow to form the high quality flow 177, one or more holes 204 may be formed along the U-tube, including in the lower portion 198. The hole sizing and locations are configured to provide the desired quality of two phase mixture entering the SLHX and/or compressor. An exemplary hole size for a drilled hole is 0.01 inch-0.5 inch (0.25 mm-12.7 mm), more narrowly 0.2-0.3 inch (5.1-7.6 mm). Multiple holes may be used and may be placed to achieve desired results.
To provide the small amount of gas in the low quality flow 179, one or more vapor line tubes 220 may extend from a portion 222 having one or more gas inlets (holes) 224 in the headspace. An exemplary portion 222 is a closed end upper portion. A second portion 226 (a lower portion) has one or more holes 228 within the liquid accumulation 200. The sizes of the holes 228 and 224 are selected so that a flow 230 of gaseous refrigerant is drawn through the holes 224 and becomes entrained in a flow of liquid refrigerant 232 drawn through the holes 228 to provide the desired composition of the low quality flow 179. Exemplary size for the holes 224 is up to two inches (50 mm) in diameter for drilled holes or equivalent area for others, more narrowly, 0.1-0.5 inches (2.5-13 mm) or 0.1-0.3 inches (2.5-7.6 mm). Exemplary size for the holes 228 is 0.1-2 inches in diameter for drilled holes or equivalent area for others, more narrowly f 0.2-1.0 inches (5-25 mm) or 0.25-0.75 inches (6.35-19.1 mm). The ratio of hole sizes (224 vapor to 228 liquid) is 0 to 0.9; more narrowly 0.1 to 0.5; more narrowly 0.1 to 0.3.
The separators may also be used as flash tank economizers.
The systems may be fabricated from conventional components using conventional techniques appropriate for the particular intended uses.
Although embodiments are described above in detail, such description is not intended for limiting the scope of the present disclosure. It will be understood that various modifications may be made without departing from the spirit and scope of the disclosure. For example, when implemented in the remanufacturing of an existing system or the reengineering of an existing system configuration, details of the existing configuration may influence or dictate details of any particular implementation. Accordingly, other embodiments are within the scope of the following claims.
Benefit is claimed of U.S. Patent Application Ser. No. 61/367,086, filed Jul. 23, 2010, and entitled “Ejector Cycle Refrigerant Separator”, the disclosure of which is incorporated by reference herein in its entirety as if set forth at length.
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