CN217274955U

CN217274955U - System and device for energy recovery

Info

Publication number: CN217274955U
Application number: CN202090000726.4U
Authority: CN
Inventors: 莫志贤
Original assignee: Zhongke Intelligent Co Ltd
Current assignee: Zhongke Intelligent Co Ltd
Priority date: 2019-05-27
Filing date: 2020-05-20
Publication date: 2022-08-23
Anticipated expiration: 2030-05-20
Also published as: AU2020286146A1; WO2020242289A1

Abstract

A system and apparatus for energy recovery, an evaporator (1) for use in a cooling subsystem (2) of an energy recovery system, the evaporator (1) being adapted to receive a refrigerant liquid and expand the refrigerant into a gas phase and a liquid phase, an exchanger device (3) for providing heat to boil the refrigerant liquid at low pressure while extracting heat from a fluid heat exchange medium and an integral subcooling device (4) to further superheat the refrigerant vapor for supply to a compressor (5) of the energy recovery system.

Description

System and device for energy recovery

Technical Field

The invention relates to a system and a device for energy recovery. More particularly, the present invention relates to energy recovery systems for cooling systems and chiller systems.

Background

Currently, government agencies and industries are moving towards energy saving devices, striving to maintain low energy consumption buildings, protect energy resources, reduce carbon emissions, reduce greenhouse gas emissions, reduce global warming and other environmental impacts. Stringent regulations are imposed on the minimum energy requirements and energy levels of major energy-related equipment, such as air conditioning and heating equipment, which consume a large portion of the generated energy. In cooling system applications, when the refrigerant is in an undesirable state (e.g., a mixture of gas and refrigerant liquid), its compressor requires more energy to compress the refrigerant discharged from the evaporator. Thus, innovative solutions and breakthrough technologies are needed in the global energy efficiency challenge.

There are several patented technologies related to heat recovery systems and devices, as compared to the prior art. US8353175B2 discloses a system comprising a plurality of roof HVAC units having a centralized refrigeration unit and describes a method of retrofitting an existing stand-alone HVAC unit into the system. The resulting multi-unit system provides greater efficiency and reliability as compared to independently operating HVAC devices.

Another system and device is disclosed in WO2008079829a 2. A cooling system for providing conditioned air to a facility is provided that includes a chiller or other cooling subsystem, a cooling tower subsystem, and one or more air handling devices or process cooling devices. The cooling subsystem may advantageously include one or more coolers (e.g., variable speed coolers, constant speed coolers, absorption coolers, etc.) and a coolant pump. The cooling tower subsystem includes one or more cooling tower devices and a condensate pump. In some embodiments, the air treatment device has a cooling coil and a variable volume fan. In some embodiments, a direct expansion (DX) cooling system includes a compressor, an evaporator, and an air-cooled, water-cooled, or evaporatively-cooled condensing system. Such systems may be controlled to reduce energy waste, improve user comfort, and/or improve thermal characteristics of the process cooling device. The cooling system also includes a control system configured to evaluate a cooling load value at the air handling device and calculate at least one operating set point using the cooling load value. The operating set point may advantageously be selected to improve the energy efficiency of the overall cooling system.

However, the systems disclosed in US8353175B2 and WO2008079829a2 do not suggest combining a cooling system and a chiller system for energy recovery.

The present invention therefore provides a system and apparatus that desirably reduces the energy consumption of the cooling system and chiller system in the system through energy recovery.

Disclosure of Invention

It is an object of the present invention to provide an energy recovery system for increasing the energy efficiency of a chiller or refrigeration system by reducing the power consumption of the compressor without compromising the final cooling capacity of the system.

In a first aspect of the invention, there is provided an evaporator for use within a cooling subsystem of an energy recovery system, the evaporator being adapted to receive a refrigerant liquid and expand the refrigerant into vapor and liquid phases, providing a heat exchanger device to boil the refrigerant liquid at a low pressure while extracting heat from a fluid heat exchange medium and an integral subcooling device to further superheat the refrigerant vapor for supply to a compressor of the energy recovery system.

In this aspect of the invention, the evaporator may comprise first and second sections for housing the integrated subcooling device and heat exchanger device, respectively.

In this aspect of the invention, the integrated subcooling device may include an inlet tube for receiving refrigerant liquid from the condenser and an outlet tube for discharging refrigerant liquid to the expansion valve.

In this aspect of the invention, the expansion valve may expand the received refrigerant liquid into a vapor phase and a liquid phase.

In this aspect of the invention, the inlet pipe and the outlet pipe may be arranged horizontally within the first section, wherein the inlet pipe is arranged at a higher level than the outlet pipe.

In this aspect of the invention, the heat exchanger device may comprise a plurality of equidistantly distributed tubes carrying a fluid heat exchange medium.

In this aspect of the invention, the evaporator can further include a eliminator plate disposed in the first section for promoting uniform flow of refrigerant vapor through the integrated subcooling device.

In another aspect of the invention, an energy recovery system is provided, comprising a compressor subsystem, a heat rejection subsystem and a cooling subsystem, wherein the compressor subsystem includes at least one compressor for drawing in superheated refrigerant vapor for compression into a high pressure hot gas, a discharge line, a condenser for delivering high pressure hot gas to the heat rejection subsystem for condensing the high pressure hot gas to refrigerant liquid while rejecting refrigeration heat, and a liquid tube, integral subcooling means for delivering a refrigerant liquid to an evaporator in the cooling subsystem, the evaporator being adapted to expand the refrigerant liquid into a mixture of vapor and liquid phases, providing heat exchanger means to boil the refrigerant liquid at low pressure, while extracting heat from the fluid heat exchange medium, and an integral subcooling device to further superheat the refrigerant vapor for supply to the compressor of the energy recovery system.

In this aspect of the invention, the heat rejection subsystem may further include a desuperheater having a heat exchanger apparatus to provide a fluid heat exchange medium for absorbing heat from the compressed refrigerant to the fluid heat exchange medium.

In this aspect of the invention, the fluid heat exchange medium in the heat exchanger arrangement may be transferred to the chiller subsystem to absorb heat emitted from the chiller subsystem and delivered to the evaporator upon absorption of the heat.

Those skilled in the art will readily appreciate that the present invention is well adapted to carry out the objects and obtain the ends and advantages mentioned, as well as those inherent therein, and that the embodiments described herein are not intended as limitations on the scope of the invention.

Drawings

For the purposes of promoting an understanding of the invention, there is shown in the drawings embodiments which are presently preferred, the invention, its construction and operation, and many of its advantages will be readily understood and appreciated when considered in connection with the following description.

FIG. 1 illustrates a side view of an evaporator used within a cooling subsystem of an energy recovery system;

FIG. 2 illustrates a cross-sectional view of an evaporator for the energy recovery system cooling subsystem; and

FIG. 3 illustrates a schematic diagram of an energy recovery system including a compressor subsystem, a heat rejection subsystem, and a cooling subsystem.

Detailed Description

Before discussing various embodiments of the invention, the following provides a description of some terms used herein in order to better understand the invention.

Herein, "energy recovery" refers to any technique or method that minimizes the energy input to an overall system by exchanging energy from one subsystem to another subsystem of the overall system.

Herein, "refrigerant" refers to a substance used in a heat pump and a refrigeration cycle, which undergoes a phase change between gas and liquid. The refrigerant readily absorbs heat from the environment and, when combined with other components such as the compressor and evaporator, can provide refrigeration or air conditioning. By way of example, but not limitation, refrigerants include chlorofluorocarbon refrigerants, and hydrofluorocarbon refrigerants, as well as natural refrigerants. Gaseous and liquid phase refrigerants may be referred to as refrigerant vapor and refrigerant liquid, respectively.

Herein, "fluid heat exchange medium" refers to a liquid or gas that transfers heat from one component to another component in any process that requires heating or cooling or is simply to maintain a constant temperature. One commonly used fluid heat exchange medium is water, which has thermodynamic properties that facilitate heat transfer.

The invention will now be described in more detail by way of example with reference to the accompanying drawings.

Fig. 1 and 2 illustrate an evaporator 1 for use within a cooling subsystem 2 of an energy recovery system. In a preferred embodiment, the evaporator 1 is in the form of a water tank having a substantially cylindrical hollow body 21, the two distal ends of which are each secured by a dome-shaped cap 19. Preferably, the evaporator 1 is lifted from the ground by a plurality of pedestal brackets 20 extending downward from the evaporator 1. In the exemplary embodiment, evaporator 1 is adapted to receive a refrigerant liquid and expand the refrigerant into a vapor phase and a liquid phase. For example, the refrigerant is refrigerant R134 a. Preferably, the evaporator 1 comprises a first portion and a second portion for housing the integrated subcooling means 4 and the heat exchanger means 3, respectively, therein.

The integrated subcooling device 4 according to the present invention comprises an inlet pipe 14 for receiving refrigerant liquid from the condenser 9 and an outlet pipe 15 for discharging refrigerant liquid to the expansion valve 13. Preferably, the inlet pipe 14 and the outlet pipe 15 are horizontally suspended in the first part, wherein the inlet pipe 14 is arranged at a higher level than the outlet pipe 15. The inlet tube 14 and the outlet tube 15 are both supported by a tube sheet 27. Preferably, the inlet and outlet pipes 14, 15 are horizontally oriented for minimizing vertical offset elimination of oil logging within the integrated subcooling device 4, particularly when the energy recovery system is operating under part load conditions. Further, when the inlet pipe 14 is placed at a higher position than the outlet pipe 15, this arrangement reduces the operating pressure, thereby reducing power consumption. The integrated supercooling apparatus 4 may have more than one inlet pipe 14 and one outlet pipe 15 to minimize a pressure loss of the refrigerant liquid flowing through the pipes 14, 15.

The expansion valve 13 or electronic expansion valve may be used interchangeably with the metering device and the throttling device. The expansion valve 13 expands the received refrigerant liquid into a vapor phase and a liquid phase, the mixture of refrigerant vapor and refrigerant liquid preferably entering the tank through the second section.

When the second portion is located below the first portion, the refrigerant liquid entering the tank floods the second portion, resulting in the heat exchanger device 3 being at least partially submerged in the refrigerant liquid. Therefore, the evaporator 1 is also referred to as a submerged evaporator. The evaporator 1 further comprises a sight glass 22 for observing the level of refrigerant liquid in the second portion, and a float for controlling the level of refrigerant liquid.

Preferably, the heat exchanger device 3 carries a fluid heat exchange medium to be delivered to and received from the other subsystem. In a particular embodiment, the heat exchanger device 3 comprises a plurality of equidistantly distributed tubes carrying a fluid heat exchange medium. For example, the tubes may be closely packed such that the fluid heat exchange medium rejects heat to a refrigerant liquid in contact with the tubes. The fluid heat exchange medium to be used depends on the subsystem connected to the heat exchanger device 3. For example, but not limiting of, the heat exchanger device 3 may be connected to the chiller subsystem 11, and the fluid heat exchange medium may be in the form of water. The heat exchanger device 3 thus boils the refrigerant liquid at low pressure while extracting heat from the water to cool the water. The cooled water is then delivered to the chiller subsystem 11 for distribution to other facilities, such as buildings.

The refrigerant liquid boiled by the heat exchanger device 3 is evaporated into refrigerant vapor. The refrigerant vapor produced by boiling of the heat exchanger means 3 and expanded refrigerant vapor entering through the second portion of the expansion valve 13 rise to the first portion and contact the integrated subcooling means 4. Advantageously, the first section also includes a eliminator plate 18 for promoting uniform flow of refrigerant vapor through the integrated subcooling device 4. The integral subcooling device 4 further superheats the refrigerant vapor by absorbing heat from the refrigerant liquid to be supplied to the compressor 5 of the energy recovery system. After the heat is removed, the refrigerant liquid within the integrated subcooling device 4 becomes subcooled refrigerant liquid having a reduced enthalpy with a corresponding increase in net enthalpy.

In the inlet state of the compressor 5, the level of superheated refrigerant vapor increases. The superheated refrigerant vapor absorbs additional heat in the vapor compression cycle and increases its energy level at the outlet conditions of the compressor 5. In other words, the additional heat obtained from the subcooled refrigerant liquid is transferred to the high pressure hot gas produced by the compressor 5.

This process is accompanied by a decrease in the superheated refrigerant vapor density. Therefore, the displacement of the compressor 5 is reduced due to the reduced mass flow rate of the replacement refrigerant. However, this arrangement does not affect the ultimate cooling capacity of the energy recovery system. The increase in net enthalpy of the subcooled refrigerant liquid offsets the capacity loss of the compressor 5. The reduction in the density of the superheated refrigerant vapor at the inlet of the compressor 5 results in a reduction in the work performed by the compressor 5, since the compressor power is proportional to the density of the refrigerant vapor at the inlet of the compressor 5.

The evaporator 1 may further comprise a liquid line inlet connection 24 for connecting the integrated subcooling device 4 to the condenser 9, a liquid line outlet connection 25 for connecting the integrated subcooling device 4 to the expansion valve 9 and a distributor 28 arranged in the second section.

Preferably, the evaporator 1 is adapted to be used with a refrigerant having a high specific heat capacity in the vapor phase. Synthetic lubricating oils are preferred because they are more stable at higher temperatures.

Advantageously, as the degree of superheat of the discharge increases, the oil separation between the lubricating oil and the refrigeration oil is improved. The properties and performance of the lubricating oil must be miscible with the refrigerant. Therefore, oil delivery from the compressor 5 or oil separator is unavoidable. However, as the discharge temperature increases relative to the condensing temperature (i.e., discharge superheat), the rate of oil loss decreases. On the other hand, the performance of the condenser 9 and the evaporator 1 is improved, and the lubricating oil flowing into these parts of the system is reduced, thereby functioning as an insulator for heat transfer of the refrigerant. Further, as the suction superheat, discharge superheat, and oil loss increase, the life expectancy of the compressor 5 is extended.

The energy recovery system shown in fig. 3 also includes a compressor subsystem 6 and a heat rejection subsystem 7. The compressor subsystem 6 includes at least one compressor 5, the compressor 5 being coupled to an electric motor 26 for drawing in superheated refrigerant vapor for compression to a high pressure hot gas. The compressor 5 may be a positive displacement refrigeration compressor that draws in refrigerant vapor and compresses the refrigerant vapor into a high pressure hot gas of elevated boiling point.

The energy recovery system further comprises a discharge pipe 8 for conveying the high pressure hot gas to a condenser 9 within the heat rejection subsystem 7 for condensing the high pressure hot gas into a refrigerant liquid while rejecting the refrigeration heat. The condenser 9 may be an air-cooled condenser or a water-cooled condenser. The air-cooled condenser consists of a finned coil and a fan motor. The air-cooled condenser is used to discharge cooling heat to the air flowing through the coil while condensing the cooled high-pressure hot gas into refrigerant liquid. On the other hand, the water-cooled condenser is composed of a shell-and-tube heat exchanger for discharging cooling heat into water circulating through tubes while condensing the cooled high-pressure hot gas into a refrigerant liquid. The condenser 9 may be connected to a cooling water system 16. The cooling water system may comprise a cooling water pump for circulating cooling water between the condenser 9 and the cooling tower system.

The refrigerant liquid is delivered to the integral subcooling device 4 of the evaporator 1 in the cooling subsystem 2 through liquid line 23. In a particular embodiment, the evaporator 1 is adapted to expand refrigerant liquid into a mixture of gas and liquid phases. The heat exchanger device 3 in the evaporator 1 is used to boil refrigerant liquid at low pressure while extracting heat from the fluid heat exchange medium. The integrated subcooling device 4 further superheats the refrigerant vapor so that superheated gas refrigerant is drawn into the compressor 5 by means 17 to be supplied to the compressor 5 of the energy recovery system.

Preferably, the fluid heat exchange medium in the heat exchanger device 3 is transferred to the chiller subsystem 11 to absorb heat emanating from the chiller subsystem 11 and is delivered to the evaporator 1 upon absorption of the heat. In one particular embodiment, the chiller subsystem 11 is a hydraulic pumping system having a chilled water circulation pump for circulating and distributing chilled water to a dry side device or other process.

The heat rejection subsystem 7 may also include a desuperheater 12 having a heat exchanger apparatus 10 to provide a fluid heat exchange medium for absorbing heat from the compressed refrigerant to the fluid heat exchange medium. In a particular embodiment, the heat exchanger device 10 may be a brazed plate heat exchanger or a shell and tube heat exchanger. The heat exchanger device 10 is used for recovering cooling heat from a desuperheating process, mainly for domestic hot water consumption.

The invention comprises the subject matter contained in the appended claims, as well as in the foregoing description. Although the invention has been described in its preferred form with a certain degree of particularity, it is understood that the present invention is in the preferred form as an example only and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the scope of the invention.

Claims

1. An evaporator (1) for use within a cooling subsystem (2) of an energy recovery system, the evaporator (1) being adapted to receive a refrigerant liquid and expand the refrigerant into a gas phase and a liquid phase, a heat exchanger device (3) for providing boiling of the refrigerant liquid at a low pressure while extracting heat from a fluid heat exchange medium and an integral subcooling device (4) to further superheat the refrigerant vapor for supply to a compressor (5) of the energy recovery system, wherein the integral subcooling device (4) comprises an inlet tube (14) and an outlet tube (15), the inlet tube (14) and the outlet tube (15) both being arranged horizontally within a first portion, wherein the inlet tube (14) is arranged at a higher level than the outlet tube (15).

2. Evaporator (1) according to claim 1, wherein the evaporator further comprises a second portion for accommodating the heat exchanger device (3).

3. Evaporator (1) according to claim 2, wherein the inlet pipe (14) is for receiving refrigerant liquid from the condenser (9) and the outlet pipe (15) is for discharging refrigerant liquid to the expansion valve (13).

4. Evaporator (1) according to claim 3, wherein the expansion valve (13) expands the received refrigerant liquid into a gas phase and a liquid phase.

5. Evaporator (1) according to claim 3, wherein the heat exchanger device (3) comprises a plurality of equidistantly distributed tubes carrying a fluid heat exchange medium.

6. The evaporator (1) of claim 2, further comprising an eliminator plate (18) disposed in the first section for promoting uniform flow of refrigerant vapor through the integrated subcooling device (4).

7. An energy recovery system comprising a compressor subsystem (6), a heat rejection subsystem (7) and a cooling subsystem (2), wherein the compressor subsystem (6) comprises at least one compressor (5) for drawing in superheated refrigerant vapour for compression into high pressure hot gas, and a discharge conduit (8) for conveying the high pressure hot gas to a condenser (9) within the heat rejection subsystem (7) for condensing the high pressure hot gas into refrigerant liquid while rejecting heat of refrigeration, and a liquid line for conveying the refrigerant liquid to an integral subcooling device (4) of an evaporator (1) within the cooling subsystem (2), the evaporator (1) being adapted to expand the refrigerant liquid into a mixture of a gas phase and a liquid phase, heat exchanger means (3) being provided to boil the refrigerant liquid at low pressure while extracting heat from the fluid heat exchange medium and the integral subcooling device (4) to further superheat the refrigerant vapour, to be supplied to a compressor (5) of the energy recovery system.

8. The energy recovery system according to claim 7, wherein the heat rejection subsystem (7) further comprises a desuperheater (12), the desuperheater (12) having a heat exchanger apparatus (10) for providing a fluid heat exchange medium to absorb heat from the compressed refrigerant into the fluid heat exchange medium.

9. The energy recovery system according to claim 7, wherein the fluid heat exchange medium in the heat exchanger device (3) is transferred to the chiller subsystem (11) for absorbing heat emanating from the chiller subsystem (11) and being transported to the evaporator (1) upon absorption of the heat.