WO2015024155A1

WO2015024155A1 - Gas cooler

Info

Publication number: WO2015024155A1
Application number: PCT/CN2013/081732
Authority: WO
Inventors: Long Zhang
Original assignee: Trane Air Conditioning Systems (China) Co., Ltd.; Trane International Inc.
Priority date: 2013-08-19
Filing date: 2013-08-19
Publication date: 2015-02-26
Also published as: CN105518407A; CN105518407B; JP2016528471A; JP6346285B2

Abstract

Methods, systems and apparatus that are configured to reduce a temperature change of a cooling fluid at where the CO₂may have a relatively high specific heat capacity in a gas cooler are provided. Additional cooling fluid can be introduced to where the CO₂may have a relativelyhigh specific heat capacity to reduce the temperature change of the cooling fluid. By slowing down the temperature change of the cooling fluid at where the CO₂may have the relatively high specific heat capacity, a temperature differential between the CO₂and the cooling fluid in the gas cooler can be maintained and/or created, which may help heat exchange between the CO₂and the cooling fluid.

Description

GAS COOLER

Field

The disclosure herein generally relates to a heating, ventilation, and air-conditioning ("HVAC") system. More specifically, the disclosure herein relates to a gas cooler of a heat pump using C0₂ as a refrigerant in a HVAC system. Generally, methods, systems, and apparatuses are described that are directed to help increase heat exchange efficiency of the g cooler of the C0₂ heat pump. Background

Due to for example global environmental concerns, natural working fluids (such as C0₂) have been increasingly used as refrigerant in a HVAC system, such as in a heat pump system of the HVAC system. Using natural working fluids (such as C0₂) can help reduce, for example, global warming potential (GWP) of the HVAC system.

A C0₂heat pump system typically includes a compressor that is configured to compress the C0₂. The compressed C0₂ can be directed into a gas cooler. In the gas cooler, the compressed C0₂ can reject heat to, for example, a cooling fluid (such as water) and reduce the temperature of the compressed C0₂. The C0₂ can then be directed into an expansion device and then into an evaporator to exchange heat with a processing fluid (such as air or water). The processing fluid can be used, for example, to condition an interior space of a building. The cooling fluid (such as water), after being heated in the gas cooler, can be used to, for example, provide hot utility water. The heat rejection process in the gas cooler can happen at a temperature that is above the critical point of the C0₂, hence the heat pump system may be called a trans-critical system_.

Summary

Methods, systems and apparatus configured to help increase heat exchange efficiency in a HVAC system using a natural working fluid, particularly C0₂, are provided. It is understood that the embodiments disclosed herein may be used with other types of natural working fluids.

In some embodiments, a temperature change of a cooling fluid can be reduced at where C0₂ may have a relatively high cp-value (or specific heat capacity) in a gas cooler. In some embodiments, an extra amount of cooling fluid may be introduced into the gas cooler at where the CO2 may have the relatively high cp-value (or specific heat capacity) to reduce the temperature change of the cooling fluid. By slowing down the temperature change of the cooling fluid at where the C0₂ may have the relatively high cp-value (or specific heat capacity), a temperature differential between the C0₂ and the cooling fluid in the gas cooler can be maintained and/or created, which may help improve heat exchange between the C0₂ and the cooling fluid.

In some embodiments, a gas cooler may include a gas passage that has a gas inlet and a gas outlet, and a cooling fluid passage. The cooling fluid passage may include a first cooling fluid inlet and a first cooling fluid outlet, where the first cooling fluid inlet and the first cooling fluid outlet may be in fluid communication. The cooling fluid passage may also include a second cooling fluid inlet and a second cooling fluid outlet, where the second cooling fluid inlet and the second cooling fluid outlet are in fluid communication. The gas cooler has a length and the gas passage and the cooling fluid passage may be in heat exchange relationship along the length.

In some embodiments, the second cooling fluid inlet may be configured to direct a cooling fluid into the gas cooler at a first position that is between the first cooling fluid inlet and the first cooling fluid outlet. In some embodiments, the second cooling fluid outlet may be configured to direct the cooling fluid out of the gas cooler at a second position that is between the first cooling fluid inlet and the first cooling fluid outlet. In some embodiments, the first position may be closer to the first cooling fluid inlet than the second position along the length.

In some embodiments, the first cooling fluid inlet, the second cooling fluid inlet, the second cooling fluid outlet and the first cooling fluid outlet may be all in fluid communication with the cooling fluid passage. The cooling fluid can be directed into the cooling fluid passage from the first and/or second fluid inlets and mixed in the cooling fluid passage. The cooling fluid can also be directed out of the cooling fluid passage from the first and/or second fluid outlets

In some embodiments, the first cooling fluid inlet and the first cooling fluid outlet may form a first cooling fluid path, and the second cooling fluid inlet and the second cooling fluid outlet may form a second cooling fluid path. In some embodiments, the first cooling fluid path and the second cooling fluid path may be separate.

In some embodiments, the gas cooler may be included in a HVAC system using C0₂ as refrigerant. In some embodiments, the first cooling fluid inlet may be configured to receive, for example, tap water. In some embodiments, the second cooling fluid inlet may be configured to receive a cooling fluid from, for example, a space heater.

In some embodiments, a method of managing a cooling fluid in a gas cooler may include directing a compressed gas into a gas inlet of the gas cooler and toward a gas outlet; directing a first cooling fluid into a first cooling fluid inlet of the gas cooler; and directing a second cooling fluid into a second cooling fluid inlet of the gas cooler. In some embodiments, the first cooling fluid inlet may be further away from the gas inlet of the gas cooler than the second cooling fluid inlet along a length of the gas cooler. The introduction of the second cooling fluid can reduce the temperature change of the first and/or second cooling fluids.

In some embodiments, the second cooling fluid may be introduced into the gas cooler at where the C0₂ may have a relatively high cp-value (or specific heat capacity), so that the temperature change of the first and/or second cooling fluids can be reduced at where the C0₂ may have the relatively high cp-value (or specific heat capacity.)

In some embodiments, the method of managing a cooling fluid in gas cooler may include directing the cooling fluid out of the gas cooler from a first cooling fluid outlet and a second cooling fluid outlet. In some embodiments, an amount of the cooling fluid directed out of the second cooling fluid outlet may be the same as an amount of the cooling fluid directed into the second cooling fluid inlet.

Other features and aspects of the embodiments will become apparent by consideration of the following detailed description and accompanying drawings. Brief Description of the Drawings

Reference is now made to the drawings in which like reference numbers represent corresponding parts throughout.

Fig. 1 illustrates temperature-specific enthalpy curves of C0₂ at different pressures. Fig. 2 illustrates temperature -transferred heat curves of C0₂ and a cooling fluid of a traditional C0₂ gas cooler.

Fig. 3 illustrates a representative temperature -transferred heat curve of C0₂ and a cooling fluid in as may be described in a C0₂ gas cooler as disclosed herein.

Figs. 4A and 4B illustrate an embodiment of a gas cooler. Fig. 4A is a schematic view. Fig. 4B is a perspective view.

Fig. 5 illustrates a schematic view of another embodiment of a gas cooler.

Fig. 6 illustrates a schematic view of a HVAC system that utilizes a gas cooler as disclosed herein. Detailed Description

In a HVAC system, such as a heat pump system utilizing C0₂ as a refrigerant, the C0₂ generally is compressed by a compressor and then directed into a gas cooler. In the gas cooler, the compressed C0₂ can reject heat to a cooling fluid, such as water. A heat pump system using C0₂ as a refrigerant can work as a trans-critical heat pump system. That is the refrigerant C02 in the heat pump system can go through both subcritical and supercritical states relative to its critical point. The term "critical point" is generally referred to the highest pressure and temperature where the refrigerant can still condense. At critical point, the distinct liquid and gas phases generally do not exist. The subcritical state generally refers to a state where the temperature and pressure of the refrigerant is below the critical point. The supercritical state generally refers to a state where the temperature and pressure of the refrigerant is above the critical point. In supercritical state, the distinction between gas and liquid disappears so that the refrigerant can no longer be condensed.

In a trans-critical heat pump system, the heat rejection process in the gas cooler may occur above the critical point of C0₂, i.e. the C0₂ may be in the supercritical state. In the supercritical state, the specific heat capacity (i.e. cp-value (kj/kg)) of the C0₂ is independently variable based on the pressure or the temperature of the C0₂. The term "specific heat capacity" generally means the amount of heat required to change a unit degree (e.g. 1°C) of the temperature of per unit mass (1kg) of a material (e.g. C0₂).

References are made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration of the embodiments in which the embodiments may be practiced. It is to be understood that the terms used herein are for the purpose of describing the figures and embodiments and should not be regarded as limiting the scope of the present application.

Fig. 1 illustrates temperature-specific enthalpy isobar curves for C0₂ at certain specific supercritical pressures ranging from 7.5MPa to 20MPa. Each curve corresponds to the temperature-specific enthalpy isobar curve under the marked pressure. Generally, the slopes of the curves (At/Ah) correspond inversely to the cp-value (Ah/At) at the marked pressure.

Generally, the steeper the slope is, the smaller the cp-value (or the specific heat capacity) and vice versa. When the cp-value is relatively small, the temperature of the C0₂ can be changed relatively quickly at a given amount of heat exchange.

As shown in Fig. 1 , the cp-values are not generally constant in the temperature ranges shown, i.e. the slopes of each of the curves generally vary along the curves. The curves as shown in Fig. 1 generally have a middle portion 110 that has relatively less slopes than the other portions of the curves. In the middle portion 110, the cp-value may be relatively high compared to other portions of the curves. For example, when the pressure is at about 7.5Mpa and the temperature is at about 30°C, the cp-value may be above 10,000. When the cp-value is relatively high, C0₂ can reject a given amount of heat with a relatively small temperature change.

Fig. 2 illustrates a traditional C0₂ gas cooler 200 and a temperature -transferred heat (Q) curve at a working pressure of 75bar (7.5MPa). The temperature-Q curves 202 and 204 generally represent the state of the C0₂ (202) and a cooling fluid (204) inside the gas cooler 200 along a length L2 of the gas cooler 200 respectively. Each point of the curve 202 or the curve 204 represents a point along the length L2 that has the corresponding temperature of C0₂ or the cooling fluid.

The gas cooler 200 can be a counter-flow type heat exchanger, which includes a C0₂ passage 210 and a cooling fluid (such as water) passage 220. The C0₂ passage 210 includes a C0₂ inlet 212 and C0₂ outlet 214, and the cooling fluid passage 220 includes a cooling fluid inlet 222 and a cooling fluid outlet 224. The C0₂ generally flows in a direction from the C0₂ inlet 212 (the right side of Fig. 2) toward the C0₂ outlet 214 (the left side of Fig. 2), and the cooling fluid passage generally flows in a direction from the cooling fluid inlet 222 (the left side of Fig. 2) toward the cooling fluid outlet 224 (the right side of Fig. 2). Generally, the flow direction of the C0₂ is counter, e.g. opposite, to the direction of the cooling fluid. Heat exchange can occur between the C0₂ passage 210 and the cooling fluid passage 220.

In Fig. 2, the relatively curved line 202 represents the state of C0₂ in the gas cooler 200 and the relatively straight line 204 represents the state of the cooling fluid in the gas cooler 200. The C0₂ has an inlet temperature 21 1 (e.g. about 70°C) at the C0₂ inlet 212 and an outlet temperature 213 (e.g. about 30°C) at the C0₂ outlet 214. The cooling fluid has an inlet temperature 221 (e.g. about 25°C) at the cooling fluid inlet 222 and an outlet temperature 223 (e.g. about 50°C) at the cooling fluid outlet 224.

As shown in Fig. 2, the relatively straight line 204 indicates that the temperature change of the cooling fluid is relatively constant inside the gas cooler 200 between the cooling fluid inlet 222 to the cooling fluid outlet 224 (i.e. the slopes (ΔΤ/AQ) of the line 204 is relatively constant along the line 204). The relatively curved line 202 indicates that the temperature change rate of the C0₂ is variable between the C0₂ inlet 212 and the C0₂ outlet 214 (i.e. the slopes (ΔΤ/AQ) of the line 202 varies along the line 202) along the length L2. In an area 230 of the line 202, which can correspond to a middle portion of the gas cooler 200 along the length L2, the cp-value (or the specific heat capacity) of C0₂ can be relatively high (i.e. the temperature change of C0₂ is relatively small at a given amount of heat rejection). Accordingly, the temperature differential between the C0₂ and the cooling fluid can be relatively small in the middle portion of the gas cooler 200 corresponding to the area 230 along the length L2. For example, at a pinch point 235, the temperature of the C0₂ may be about the same as the cooling fluid, causing relatively no heat exchange occurring between the C0₂ and the cooling fluid inside the gas cooler 200. This situation can reduce heat exchange efficiency, capacity and/or the exiting temperature of the C0₂ of the gas cooler 200. For example, due to the variable cp-value (or specific heat capacity) of C0₂ , the gas cooler 200 may have a portion (such as the middle portion corresponding to the portion 230 of the line 202) that may have a relatively small temperature differential between the C0₂ and the cooling fluid, resulting in relatively inefficient heat exchange in that portion of the gas cooler 200. Improvements can be made to increase the heat exchange efficiency and/or capacity of the gas cooler.

Embodiments as disclosed herein are generally directed to methods, systems and apparatus that are configured to decrease the temperature change rate of the cooling fluid at where the C0₂ may have a relatively high cp-value (or specific heat capacity) in a gas cooler. In some embodiments, decreasing the temperature change rate of the cooling fluid can be accomplished by introducing additional cooling fluid to where the C0₂ may have a relatively high cp-value (or specific heat capacity). By decreasing the temperature change rate of the cooling fluid at where the C0₂ may have the relatively high cp-value (or specific heat capacity), a temperature differential between the C0₂ and the cooling fluid in the gas cooler can be maintained and/or created, which may help heat exchange between the C0₂ and the cooling fluid.

Fig. 3 shows a temperature -transferred heat (Q) diagram of a schematic representation of a gas cooler 300 to illustrate a general principle of configuring the gas cooler 300 and also a general method of managing the cooling fluid in the gas cooler 300. The temperature-Q diagrams generally represent a temperature of C0₂ and a cooling fluid at different points along a length L3 of the gas cooler 300. Generally, curve 302 corresponds to cp-value (or specific heat capacity) or the temperature change rate at a given amount of heat (the slope of the curve 302 at a given point along the curve 302) of the C0₂ along a longitudinal direction that is defined by the length L3 of the gas cooler 300 at a given pressure (such as 7.5MPa), and curve 304 corresponds to the temperature change rate at a given amount of heat (the slope of the curve 304 at a given point along the curve 304) of a cooling fluid (such as water) along the longitudinal direction. The gas cooler 300 can be a counter-flow heat exchanger, which may include a C0₂ inlet 312 and a C0₂ outlet 314. The C0₂ generally flows in a direction from the C0₂ inlet 312 toward the C0₂ outlet 314. The gas cooler 300 can be configured to have a plurality of cooling fluid inlets, such as a first cooling fluid inlet 322 and a second cooling fluid inlet 326, which are configured to receive a cooling fluid. The gas cooler 300 can also be configured to have a plurality of cooling fluid outlets, such as a first cooling fluid outlet 324 and a second cooling fluid outlet 328, which are configured to direct cooling fluid out of the gas cooler 300. The first cooling fluid inlet 322, the second cooling fluid inlet 326, the second cooling fluid outlet 328 and the first cooling fluid outlet 324 are arranged in the longitudinal direction respectively.

In operation, as shown by the curves 302 and 304, the C0₂ is at a state that generally corresponds to point 302d when entering the gas cooler 300 and the cooling fluid is at a state that generally corresponds to point 304d when the cooling fluid exits the first cooling fluid outlet 324. The C0₂ is at a state that generally corresponds to point 302a when exiting the gas cooler 300 and the cooling fluid is at a state that generally corresponds to point 304a when the cooling fluid enters the first cooling fluid inlet 322.

As shown by the curve 302, a region 320 of the curve 302 that is generally between the points 302b and 302c can have relatively small slopes, which corresponds to a relatively high cp- value (or specific heat capacity) of C0₂. Generally, in the region 320, the temperature change rate of C0₂ may become smaller at a given amount of heat rejection. For example, when the temperature of the C0₂ is between the temperatures corresponding to the point 302b and 302c, the temperature change of the C0₂ may be relatively small at a given amount of heat rejection. Therefore, the temperature change of the C0₂ may be relatively slow in the region along the length L3 that corresponds to the region 320.

A general principle for configuring the gas cooler 300 or managing the cooling fluid in the gas cooler 300 is to position the second cooling fluid inlet 326 and the second cooling fluid outlet 328 at positions along the length L3 of the gas cooler 300 that may generally correspond to the points 302b and 302c respectively. In another word, the positions of the second cooling fluid inlet 326 and the second cooling fluid outlet 328 can be at about where the temperature of C0₂ may correspond to the temperature of C0₂ at the points 302b and 302c respectively.

By positioning the second cooling fluid inlet 326 and the second cooling fluid outlet 328 along the length L3 of the gas cooler 300 at locations that generally correspond to the points 302b and 302c respectively, extra cooling fluid (besides the cooling fluid that may be introduced into and out of the gas cooler 300 from the first cooling fluid inlet and outlet 322 and 324 respectively) can be introduced into and out of the gas cooler 300 from the second cooling fluid inlet 326 and the second cooling fluid outlet 328. As shown by the curve 304 in Fig. 3, because of the extra cooling fluid introduced into the gas cooler 300 at the portion of the gas cooler 300 that generally corresponds to the region 320, the temperature change rate of the cooling fluid in the gas cooler 300 can be reduced in the portion of the gas cooler 300 that generally corresponds to the region 320. As a result, as shown by the curve 304, the slope of the curve 304 can be relatively small in the portion that generally corresponds to the region 320. Therefore, the temperature change rate in the cooling fluid can be reduced compared to the portions of the gas cooler 300 with no extra cooling fluid (e.g. along the line 304, the slopes of the portion between 304b and 304c generally has a smaller slope compared to the portions between 304a and 304b and/or the portion between 304c and 304d).

A portion of the cooling fluid can be directed out of the second cooling fluid outlet 328. In some embodiments, the amount of the cooling fluid being directed out of the second cooling fluid outlet 328 may be about the same as the amount of the cooling fluid being directed into the gas cooler 300 through the second cooling fluid inlet 326. In some embodiments, the understanding that the amount of the cooling fluid being directed out of the second cooling fluid outlet may be different from the amount of the cooling fluid being directed into the gas cooler through the second cooling fluid inlet 326. After the portion of the cooling fluid being directed out of the gas cooler 300 through the second cooling fluid outlet 328, the temperature change rate of the cooling fluid in the gas cooler 300 can be increased. As shown by the curve 304, the slopes of the portion of the curve 304 between the points 304c and 304d is generally higher than the slopes of the portion of the curve 304 between the points 304b and 304c.

As shown by the curves 302 and 304, this configuration may help maintain/create a temperature differential between the C0₂ and the cooling fluid along the whole length L3 of the gas cooler 300, and help avoid the pinch point 235 as shown in Fig. 2 (where heat exchange between the C0₂ and the cooling fluid is about zero).

In some embodiments, the cooling fluid introduced at the second cooling fluid inlet 326 may be different from the cooling fluid introduced at the first cooling fluid inlet 322, with the notion that the cooling fluids introduced at the first and the second cooling fluid inlets 322 and 326 can be the same. In some embodiments, the temperature of the cooling fluid introduced into the gas cooler 300 at the second cooling fluid inlet 326 may be about the same as the temperature of the cooling fluid (which can be, for example, introduced into the gas cooler 300 from the first cooling fluid inlet 322) flowing by the second cooling fluid inlet 326 inside the gas cooler 300. Consequently, the temperature of the cooling fluid may have a minimal fluctuation when the cooling fluid is introduced into the gas cooler 300 through the second cooling fluid inlet 326.

Figs. 4A and 4B illustrate a gas cooler 400 that is generally configured to introduce an extra amount of cooling fluid at where C0₂ may have a relatively high cp-value (or specific heat capacity). The gas cooler 400 includes a C0₂ passage 410 and a cooling fluid passage 420. Heat exchange can occur between the C0₂ in the C0₂ passage 410 and the cooling fluid in the cooling fluid passage 420. The gas cooler 400 can be a counter-flow type heat exchanger. As shown by arrows in Fig. 4A, the flow direction of the C0₂ is generally counter, e.g. opposite, to the flow direction of the cooling fluid.

The C0₂ passage 410 has a C0₂ inlet 412 and a C0₂ outlet 414. The cooling fluid passage 420 has a first cooling fluid inlet 422, a second cooling fluid inlet 426, a second cooling fluid outlet 428 and a first cooling outlet 424 arranged respectively along a length L4 of the gas cooler 400. Referring to Fig. 3, in some embodiments, the second cooling fluid inlet 426 and the second cooling fluid outlet 428 can be positioned at locations corresponding to points 302b and 302c respectively along the length L4, i.e. the positions of the second cooling fluid inlet 426 and the second cooling fluid outlet 428 can be positioned at locations along the length L4 at where the temperatures of C0₂ correspond to the points 302b and 302c respectively.

As illustrated in Fig. 4A, the first cooling fluid inlet 422, the second cooling fluid inlet 426, the second cooling fluid outlet 428 and the first cooling outlet 424 are all in fluid communication with the cooling fluid passage 420. The first cooling fluid inlet 422 and the second cooling fluid outlet 428 can be configured to receive cooling fluid from, for example, different sources, and the cooling fluid can be mixed together in the cooling fluid passage 420.

The cooling fluid can be directed out of the cooling fluid passage 420 from the first cooling fluid outlet 424 and/or the second cooling fluid outlet 428. The cooling fluid directed out of the first cooling fluid outlet 424 and/or the second cooling fluid outlet 428 may be directed to, for example, various terminal devices for providing heat, heated water or other suitable utilities.

In operation, when the cooling fluid is directed into the second cooling fluid inlet 426, the cooling fluid can be mixed with the cooling fluid that flows from the first cooling fluid inlet 422. The additional cooling fluid adds a total mass of the cooling fluid and therefore can help reduce the rate of the temperature change of the cooling fluid in the section between the second cooling fluid inlet 426 and the second cooling fluid outlet 428. Accordingly, the gas cooler 400 can help maintain a temperature differential with the C0₂ in the gas cooler 400 at where the C0₂ may have a relatively high cp-value (or specific heat capacity), similar to what is shown in Fig. 3.

Fig. 5 illustrates a schematic diagram of another embodiment of gas cooler 500 configured to introduce an extra amount of cooling fluid at where C0₂ may have a relatively high cp-value (or specific heat capacity), which includes a refrigerant passage 510 configured to receive, for example, C0₂ and a cooling fluid passage 520. The cooling fluid passage 520 includes a first cooling fluid inlet 522 and a first cooling fluid outlet 524 that are in fluid communication to form a first cooling fluid path 521 through the main fluid passage 520. The cooling fluid can exchange heat with the C0₂ in the refrigerant passage 510.

The gas cooler 500 is configured to include a second cooling fluid path 530. The second cooling fluid path 530 has a length L6 in a longitudinal direction that is defined by a length L5 of the gas cooler 500. The length L6 is generally shorter than the length L5. The second cooling fluid path 530 can be positioned inside the first cooling fluid path 521 between the first cooling fluid inlet 522 and the first cooling fluid outlet 524, and generally occupies a middle portion of the gas cooler 500. Referring to Fig. 3, in some embodiments, the length L6 of the second cooling fluid path 530 and the position of the second cooling fluid path 530 can be configured to correspond to the region 320, where the C0₂ generally has a relatively large cp-value (or specific heat capacity).

The second cooling fluid path 530 includes a second cooling fluid inlet 532 and a second cooling fluid outlet 534 that are in fluid communication through the second cooling fluid path 530. The second cooling fluid path 530 is generally separate from and not in fluid

communication with the first cooling fluid path 521. In some embodiments, the cooling fluid in the second cooling fluid path 530 can be different from the cooling fluid in the first cooling fluid path 521.

In operation, when the cooling fluid is directed into the second fluid passage 530, the cooling fluid in the second fluid passage 530 can also exchange heat with the C0₂ in the refrigerant passage 510 and/or exchange heat with the cooling fluid in the first cooling fluid path 521. As a result, the temperature changes for the cooling fluid in the first fluid path 521 and/or the cooling fluid in the second fluid passage 530 can be reduced in the middle section (along the length L6) of the gas cooler 500. Accordingly, the gas cooler 400 can help maintain a temperature differential with the C0₂ in the gas cooler 500 at where the C0₂may have a relatively high cp-value (or specific heat capacity), similar to what is shown in Fig. 3.

The gas cooler as disclosed herein can be used with for example, a heat pump to heat a working fluid, such as water. Fig. 6 illustrates one embodiment of a heat pump system 600 that may use C0₂ as a refrigerant. The heat pump system 600 generally includes a compressor 610, a gas cooler 620, an expansion device 630 and an evaporator 640. The heat pump system 600 may also include other components such as a liquid/gas separator 650 and an intermediate heat exchanger 660.

In the illustrated embodiment as shown in Fig. 6, the gas cooler 620 can be configured similarly to the gas cooler 400 as illustrated in Figs. 4A and 4B. It is to be appreciated that other embodiments, including the gas cooler 500 as illustrated in Fig. 5, can also be used.

The gas cooler 620 is conflgured to include a first cooling fluid inlet 622, a second cooling fluid inlet 626, a second cooling fluid outlet 628 and a first cooling fluid outlet 624. The first cooling fluid inlet 622 and the second cooling fluid inlet 626 can be configured to receive the cooling fluid from different sources. For example, the first cooling fluid inlet 622 can be configured to receive city tap water. The second cooling fluid inlet 626 can be configured to receive water from a terminal device, such as a heat exchanger 670 for space heating. The first cooling fluid outlet 624 can be configured to direct heated water to, for example, a hot water storage tank 680 for use. The second fluid outlet 628 can be configured to direct heated water to the space heating heat exchanger 670.

The embodiments as disclosed herein can generally help maintain heat exchange between a refrigerant (i.e. C0₂) and a cooling fluid through a whole length of a gas cooler. The embodiments as disclosed herein can be manufactured as a single gas cooler, reducing manufacturing and/or installation costs. The gas cooler can also be configured to receive cooling fluid from different sources and help distribute the cooling fluid for different applications with relatively high heat transfer efficiency.

It is to be appreciated that the configuration of the heat pump system 600 is exemplary.

The gas cooler 620 can be configured to receive and/or direct the cooling fluid to other suitable devices or for other utilities.

Any aspects 1 to 3 can be combined with any aspects 4-13. Any aspects 4-8 can be combined with any aspects 9-13.

Aspect 1. A gas cooler, comprising:

a gas passage including a gas inlet and a gas outlet;

a cooling fluid passage;

a first cooling fluid inlet and a first cooling fluid outlet, the first cooling fluid inlet and the first cooling fluid outlet in fluid communication; and

a second cooling fluid inlet and a second cooling fluid outlet, the second cooling fluid inlet and the second cooling fluid outlet in fluid communication;

Wherein the gas cooler has a length, the gas passage and the cooling fluid passage are in heat exchange relationship along the length, the second cooling fluid inlet is configured to direct a cooling fluid into the gas cooler at a first position that is between the first cooling fluid inlet and the first cooling fluid outlet,

the second cooling fluid outlet is configured to direct the cooling fluid out of the gas cooler at a second position that is between the first cooling fluid inlet and the first cooling fluid outlet; and

the first position is closer to the first cooling fluid than the second position along the length.

Aspect 2. The gas cooler of aspect 1 , wherein the first cooling fluid inlet, the second cooling fluid inlet, the second cooling fluid outlet and the second cooling fluid inlet are all in fluid communication in the cooling fluid passage.

Aspect 3. The gas cooler of aspects 1-2, wherein the first cooling fluid inlet and the first cooling fluid outlet form a first cooling fluid path, the second cooling fluid inlet and the second cooling fluid outlet form a second cooling fluid path, the first cooling fluid path and the second cooling fluid path are separate.

Aspect 4. A HV AC system using C0₂ as refrigerant, comprising:

a compressor;

a gas cooler, the gas cooler configured to receive compressed C0₂ from the compressor; the gas cooler including:

a gas passage including a gas inlet and a gas outlet;

a cooling fluid passage;

Wherein the gas cooler has a length, the gas passage and the cooling fluid passage are in heat exchange relationship along the length,

the second cooling fluid inlet is configured to direct a cooling fluid into the gas cooler at a first position that is between the first cooling fluid inlet and the first cooling fluid outlet,

the second cooling fluid outlet is conflgured to direct the cooling fluid out of the gas cooler at a second position that is between the first cooling fluid inlet and the first cooling fluid outlet; and

the first position is closer to the first cooling fluid inlet than the second position along the length.

Aspect 5. The HVAC system of aspect 4, wherein the first cooling fluid inlet, the second cooling fluid inlet, the second cooling fluid outlet and the first cooling fluid outlet are all in fluid communication in the cooling fluid passage.

Aspect 6. The HVAC system of aspects 4-5, wherein the flrst cooling fluid inlet and the first cooling fluid outlet form a flrst cooling fluid path, the second cooling fluid inlet and the second cooling fluid outlet form a second cooling fluid path, the first cooling fluid path and the second cooling fluid path are separate.

Aspect 7. The HVAC system of aspects 4-6, wherein the first cooling fluid inlet is configured to receive tap water.

Aspect 8. The HVAC system of aspects 4-7, wherein the second cooling fluid inlet is configured to receive a cooling fluid from a space heater.

Aspect 9. A method of managing a cooling fluid in a gas cooler, comprising:

directing a compressed gas into a gas inlet of the gas cooler and toward a gas outlet; directing first cooling fluid into a first cooling fluid inlet of the gas cooler; and directing second cooling fluid into a second cooling fluid inlet of the gas cooler, wherein the first cooling fluid inlet is further away from the gas inlet of the gas cooler than the second cooling fluid inlet along a length of the gas cooler.

Aspect 10. The method of aspect 9, further comprising:

directing the first cooling fluid out of the gas cooler from a first cooling fluid outlet; and directing the second cooling fluid out and a second cooling fluid outlet.

Aspect 11. The method of aspects 9-10, wherein the first cooling fluid and the second cooling fluid are the same type of cooling fluid. Aspect 12. The method of aspects 9-1 1 , wherein the first cooling fluid and the second cooling fluid are mixed within the gas cooler.

Aspect 13. The method of aspects 9-12, wherein the first cooling fluid and the second cooling fluid are directed through a first cooling fluid path and a second cooling fluid path, and the first cooling fluid path and the second cooling fluid path are separate.

With regard to the foregoing description, it is to be understood that changes may be made in detail, without departing from the scope of the present invention. It is intended that the specification and depicted embodiments are to be considered exemplary only, with a true scope and spirit of the invention being indicated by the broad meaning of the claims.

Claims

Claims What claimed is:

1. A gas cooler, comprising:

a gas passage including a gas inlet and a gas outlet;

a cooling fluid passage;

2. The gas cooler of claim 1 , wherein the first cooling fluid inlet, the second cooling fluid inlet, the second cooling fluid outlet and the second cooling fluid inlet are all in fluid communication in the cooling fluid passage.

3. The gas cooler of claim 1 , wherein the first cooling fluid inlet and the first cooling fluid outlet form a first cooling fluid path, the second cooling fluid inlet and the second cooling fluid outlet form a second cooling fluid path, the first cooling fluid path and the second cooling fluid path are separate.

4. A HVAC system using C0₂ as refrigerant, comprising:

a compressor;

a gas passage including a gas inlet and a gas outlet;

a cooling fluid passage;

5. The HVAC system of claim 4, wherein the first cooling fluid inlet, the second cooling fluid inlet, the second cooling fluid outlet and the first cooling fluid outlet are all in fluid

communication in the cooling fluid passage.

6. The HVAC system of claim 4, wherein the first cooling fluid inlet and the first cooling fluid outlet form a first cooling fluid path, the second cooling fluid inlet and the second cooling fluid outlet form a second cooling fluid path, the first cooling fluid path and the second cooling fluid path are separate.

7. The HVAC system of claim 4, wherein the first cooling fluid inlet is configured to receive tap water.

8. The HVAC system of claim 4, wherein the second cooling fluid inlet is configured to receive a cooling fluid from a space heater.

9. A method of managing a cooling fluid in a gas cooler, comprising:

10. The method of claim 9, further comprising:

11. The method of claim 9, wherein the first cooling fluid and the second cooling fluid are the same type of cooling fluid.

12. The method of claim 9, wherein the first cooling fluid and the second cooling fluid are mixed within the gas cooler.

13. The method of claim 9, wherein the first cooling fluid and the second cooling fluid are directed through a first cooling fluid path and a second cooling fluid path, and the first cooling fluid path and the second cooling fluid path are separate.