MX2007012510A

MX2007012510A - Parallel-flow evaporators with liquid trap for providing better flow distribution.

Info

Publication number: MX2007012510A
Application number: MX2007012510A
Authority: MX
Inventors: Michael F Taras; Alexander Lifson
Original assignee: Carrier Corp
Priority date: 2005-05-24
Filing date: 2005-05-24
Publication date: 2007-11-09
Also published as: AU2005332040A1; HK1120600A1; CN100554833C; EP1883771A4; WO2006127001A3; CN101180506A; AU2005332040B2; EP1883771A2; JP2008542677A; CA2604466A1; US20090229282A1; BRPI0520260A2; WO2006127001A2

Abstract

A parallel-flow evaporator has a liquid trap for regulating velocity of refrigerant delivered to an evaporator from an expansion device. In its simplest configuration, the liquid trap is a u-shaped pipe positioned vertically and connected to an inlet manifold of the evaporator. By providing a liquid trap, a small amount of liquid refrigerant separates from the vapor phase at certain conditions. This separated liquid will tend to collect in the trap, and reduce a flow cross-sectional area of the line leading to the inlet manifold of the evaporator. As this cross-sectional area decreases, the velocity of the refrigerant passing through the line will increase. In this sense, as a small amount of liquid phase separates out, it will ensure that the velocity of the remaining refrigerant will increase such that further separation will be significantly reduced or entirely avoided. As a result, homogeneous refrigerant flow is provided to the evaporator, resulting in its performance enhancement and system reliability improvement.

Description

EVAPORATORS OF FLOW IN PARALLEL WITH LIQUID SIPHON TO PROVIDE BETTER DISTRIBUTION OF FLOW BACKGROUND OF THE INVENTION The invention relates to a parallel flow evaporator in which a liquid fuel is located upstream of an input co-reactor to provide better flow distribution between parallel channels, improved heat transfer and reliability of the liquid. increased system. The cooling systems are used to control the temperature and humidity of the air in various indoor environments to be conditioned. In a typical refrigerant system operating in the cooling mode, a refrigerant-e is compressed in a compressor and supplied to a condenser (or an external heat exchanger in this case). In the condenser, the heat is exchanged between the outside environmental air and coolant. From the condenser, the refrigerant passes to an expansion device, in which the refrigerant expands to a lower pressure and temperature, and then to an evaporator (or an indoor heat exchanger if the system operates in the cooling mode). In e-1 evaporator, e-1 heat is exchanged between the refrigerant and indoor air, to condition e-1 indoor air. When the refrigerant system is operating in the cooling mode, the evaporator It cools and typically dehumifies the air that is being supplied to the indoor environment. One type of evaporator that could be used in refrigerant systems is a parallel flow evaporator. Such evaporators have several parallel channels for communicating the refrigerant between an inlet manifold and an outlet manifold. Each channel typically has numerous internal parallel routes of various shapes in cross section - separated by internal walls. Corrugated fins are arranged between the channels for increased heat transfer and structural rigidity. Usually, the channels, collectors and fins are constructed of similar materials such as aluminum and are joined together by welding with brass in the furnace. Recently, parallel flow evaporators have attracted a great deal of attention and interest in the field of air conditioning due to their superior performance, compactness, rigid construction and increased resistance to corrosion. However, a problem with parallel flow evaporators is the maldistribution of the refrigerant between its channels. The problem of ma s i t r i i i i i n i in parallel flow evaporators is typically caused by the phase separation 1-iq from the. vapor in the inlet manifold due to gravity combined with -the speed of the insuf fi cient refrigerant, and in this way manifests itself in unequal amounts of vapor and liquid refrigerant passing through the evaporator channels. Additional phenomena that affect the maldis tp bucion can be attributed to different distances in which the refrigerant must flow to reach several channels and, for these channels, the unequal pressure impedances and variations in the heat transfer ratios between the channels, etc . Parallel parallel flow evaporators typically have input and output co-ectors that are indi- rect in shape. The channels are typically made of identical aluminum extrusions that form flat tubes. As the two-phase refrigerant enters the inlet manifold, the vapor phase is often separated from the liquid phase. Since the two phases will move independently of each other after the separation, the problem of ma 1 di f i coo of refrigerant often arises. When such maldistribution occurs, the performance of the heat exchanger declines rapidly, often resulting in liquid refrigerant leaving the outlet manifold. This liquid refrigerant can cause serious problems of damage and damage to the permanent compressor. Obviously, this is undesirable. BRIEF DESCRIPTION OF THE INVENTION In a disclosed embodiment of this invention, a flow evaporator is provided in parallel with a liquid siphon upstream of its inlet manifold. In this way, if the refinery is moving at such a speed that the liquid phase does not separate from the vapor phase, it can flow through the siphon, a-1 collector, and into the evaporator channels in a general distribution. same. However, if the. If the refrigerant is moving at a reduced speed, such that a liquid separation is likely to occur, then the liquid will tend to separate and accumulate in the liquid. As the liquid accumulates in the liquid siphon, the cross-sectional area of flow for the rest of the refrigerant will become smaller. Since the cross-sectional area of flow becomes smaller, then the speed of the refrigerant will increase, creating a jet effect that will carry droplets of liquid to the inlet manifold and limit the additional phase separation. This phenomenon will be self-regulating, to ensure that an adequate coolant velocity will be maintained such that the coolant will not tend to separate from the vapor. In one modality, rather than having a single U-shaped siphon, a serpentine path is used, pponporated by a number of phallic structures in the form of a u. In another disclosed modality, the system Coolant is provided with an economizer circuit, and the Liquid siphon is used on a line that directs the two-phase refrigerant mixture derived from a-1 economized heat exchanger. This modality will provide the benefit and function as with respect to the first modality disclosed. These and other features of the present invention can be better understood from the following specification and drawings, the following of which is a brief description. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a cross-sectional view of an evaporator incorporating the present invention. Figure 2 shows the evaporator of Figure 1 in a different flow condition. Figure 3 shows another modality. Figure 4 shows still another modality. DETAILED DESCRIPTION OF THE PREFERRED MODALITIES A refrigerant system 20 is illustrated in Figure 1 having a parallel flow evaporator 22. As is known, the refrigerant moves from the evaporator 22 downstream to a compressor 2? , a condenser 26, through an expansion device 28, and returns to the evaporator 22. The refrigerant left by the expansion device 28 is in a state of vapor and mixed liquid.

The evaporator 22 has a plurality of parallel channels 32 spaced along an inlet manifold 34. Channels 3? and c 1 input manifold 34 are in fluid communication with each other. In addition, the channels 32 are located in a similar manner and communicate with an outlet manifold 5. The fins 30 are disposed between the channels 32. The channels 32, the flaps 30, the inlet manifold 34 and the outlet manifold 35 are typically joined together by brass welding in the furnace. As is known, the air is passed over the fins 30 and the channels 32 to be conditioned. Due to the interaction of heat transfer with the air supplied to a conditioned space, the refrigerant evaporates inside the channels 32. As mentioned in the above, if the speed of the refrigerant approaching the inlet manifold 34 is insufficiently low, this It can cause the liquid refrigerant to separate vapor. This may result in a poor distribution of the two refrigerant phases between the channels 32. As shown in Figure 1, the refrigerant is moving at a suitable speed, and little or no separation of the refrigerant phases occurs. A tube 36 leading to the inlet manifold 34 is located downstream of a liquid siphon 38. As illustrated, the liquid siphon 38 generally extends in a u-shaped manner. So, any liquid that tends to separate will be collected in the liquid siphon 38. As shown in Figure 2, the coolant speed is Insufficiently low 'compared to the condition in Figure 1 to prevent phase separation, and a certain amount of refrigerant liquid 40 has been collected in siphon 38. As a result, the cross-sectional area 4? which remains for the refrigerant flow decreases significantly. This in turn increases the speed of the refrigerant that passes to the inlet manifold 34. If the refrigerant flow rate is increased, e-1 vapor refrigerant will tend to bring its liquid phase to the channels 3? in a homogeneous way to ensure The distribution is generally the same. In effect, a zone of jets is created to increase the speed and limit the additional phase separation. Thus, by including the liquid siphon 38 upstream of the head 34, the present invention self-regulates the speed of the refrigerant and ensures that, relative to the initial separation of a small amount of liquid refrigerant 40, e-1 remaining liquid refrigerant will tend to not to be separated from the vapor phase resulting in homogeneous flow conditions in the inlet manifold 34. Of course, the inlet manifold 34 must be of an appropriate cross-sectional area and length to support this homogeneity of flow . Also, the liquid siphon 38 should be located in close Proximity to the inlet manifold 34. Preferably, the liquid siphon 38 must be located within 5 inches from the inlet to the inlet manifold 34 and extend vertically LmenLe from under it. Consequently, the performance of-1 evaporator is improved. This will also result in no liquid refrigerant in the outlet manifold 35 of the evaporator and increase with reliability of the system. While this invention is disclosed in a conventional evaporator, other heat exchangers, for example heat exchangers economizers (or so-called shell heat exchangers welded with brass) which also have an evaporator function, they can also benefit from this invention. Further, although the liquid siphon 38 is shown in its simplest configuration, other arrangements (such as multiple u-shaped segments connected together, local flow impedances, etc.) are also feasible. Another embodiment 100 shown in Figure 3 and a plurality of u-shaped siphons in series 102 upstream of the portion 104 leading to the inlet manifold 34. Each liquid sample 102 can collect a small amount of liquid refrigerant, increasing the speed of the vapor phase and promoting homogeneous conditions at the entrance of the intake manifold 34. Another modality of the refrigerant system 110 illustrated in Figure 4. In this embodiment, a compressor 112 supplies a compressed refrigerant to a condenser 114. A line 116 is derived from a main refrigerant flow line 126, and passed through an economy expansion device Loter 118. A liquid trap 120 regulates the refrigerant that passes through an inlet 122, to an economizer heat exchanger 124. The liquid trap 120 provides the function and operates as described with respect to the modes of operation. Figure 1 and Figure 2. It should be understood that the economizer heat exchanger 124 is structured to have adjacent channels such that heat is exchanged between the refrigerant in the branch line 116 and the refrigerant at the main flow line 176. The main flow line 126 supplies Coolant to an outlet 128 and passes it through a main expansion device 130 to an evaporator 132. The present invention can utilize the liquid siphon with both the heat exchange exchanger 12.4, and the evaporator 132. The refrigerant returns from the evaporator 132 back to the compressor 112. A line 134 downstream of the economizer heat exchanger 124 returns the derived refrigerant back to an intermediate compression point in the compressor 112. It has to be pointed out that although all the input manifolds are displayed in a configuration horizontal, the phenomenon of ma 1-d -? s tri bución is more pronounced in a vertical orientation. In such circumstances, the benefits of the present invention become even more pronounced. Although a preferred embodiment of this invention has been disclosed, a worker of ordinary skill in the art will recognize that certain modifications would fall within the scope of this invention. For this reason, the following claims must be studied to determine the true and confessed scope of this invention.

Claims

CLAIMS 1. A refrigerant system, characterized in that it comprises: a compressor that supplies a compressed refrigerant to a condenser, the refrigerant that passes from the condenser to an expansion device, and from the expansion device to an evaporator, the evaporator comprising a collector of inlet, an outlet manifold, a plurality of channels receiving the refrigerant from the inlet manifold and supplying it to the outlet manifold, and fins disposed between the channels; and a line connecting the expansion device and the evaporator, the line that is provided with a liquid siphon to collect the liquid separated from a vapor refrigerant that passes from the expansion device to the evaporator. 2. The refrigerant system according to claim 1, characterized in that the liquid siphon extends vertically below the inlet manifold. 3. The refrigerant system according to claim 1, characterized in that the liquid fuel is generally provided by a u-shaped downwardly extending portion of the line. 4. The refrigerant system according to claim 1, ca acte ized because the liquid siphon It is located within 5 inches from the entrance manifold. b. The refrigerant system according to claim 1, characterized in that the refrigerant system is also provided with an economizer circuit, the economizer circuit having an economizer heat exchanger, and the economizer heat exchanger that is provided with a bypass line that connects a main flow line through an economizer expansion device, and then to the economizer heat exchanger, - the bypass line that is returned to an intermediate compression point in the compressor downstream of the economi heat exchanger i / a liquid siphon to collect the liquid separated from a vapor reflector passing the economizer expansion device a-1 economizer heat exchanger. 6. The refractive system according to claim 1, characterized in that the liquid element includes a plurality of liquid siphon portions in the form of u widely spaced. 7. A method for operating a reflectant system, characterized in that it comprises the steps of: proportioning an evaporator having a plurality of tubes receiving the refrigerant from a inlet manifold, and supply e-1 refrigerant to an outlet manifold, and from the. output manifold to the compressor, the compressor that supplies the condenser to a condenser, and refrigerant that passes from the condenser to an expansion device, and then back to the evaporator, and that provides a fluid line that connects the expansion device to the evaporator, -The fluid line that is provided with a liquid siphon to capture the liquid that has been separated from a vapor refrigerant; and passing the refrigerant through the refrigerant system and tai that the liquid siphon self regulates a speed of. coolant as the liquid separates from the vapor coolant to supply coolant to the inlet manifold in a predominantly homogeneous state. 8. The method according to claim 7, characterized in that the cooling system is further provided with a switching circuit, the economizing circuit that includes an economizer heat exchanger, and which drifts coolant and which passes the derived refrigerant through from an economizer expansion device to the economized Lor exchanger, and a liquid siphon provided to capture the liquid that has been separated from a vapor that passes from the economizer expansion device to an economized heat exchanger r, and also which includes the steps of moving to-1- refrigerant through the. economizer expansion device, and economizer heat exchanger, such that the liquid siphon auto-re-speeds a refrigerant as the liquid separates from the vapor refrigerant to supply refrigerant in the economizer heat exchanger in a state predominantly in a homogeneous way. 9. A heat exchanger and fluid line system, characterized in that it comprises: a fluid line leading to an inlet manifold; a 1-in-1 fluid on the 1 fluid line; and a heat exchanger that has a plurality of channels that receive a fluid from the inlet manifold. 10. The heat-exchanger and fluid line system according to claim 9, characterized in that the heat exchanger is a refrigerant system evaporator. 11. The fluid barrier and fluid line i-n system according to claim 9, characterized in that the heat exchanger side is a heat exchanger economizer of the refrigerant system. 12. The heat exchanger and fluid line heat exchanger system according to claim 9, characterized in that the liquid siphon extends vertically below the inlet manifold. 13. The heat exchanger and fluid line system according to claim 9, characterized in that the liquid siphon is generally provided by a u-shaped downwardly extending portion of the line. 14. The heat exchanger and fluid line system according to claim 9, characterized in that the liquid-siphon is located within 5 inches from the inlet manifold. I b. The system for exchanging heat and fluid line according to claim 1, characterized in that the liquid siphon is provided by a plurality of serially spaced u-shaped structures.