Patent Publication Number: US-11022360-B2

Title: Method for reducing condenser size and power on a heat rejection system

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is related to concurrently filed and co-pending U.S. application Ser. No. 16/380,665, titled “Method for Reducing Condenser Size and Power on a Heat Rejection System,”, first named inventor: Eric Donovan. This application is also related to concurrently filed and co-pending U.S. patent application Ser. No. 16/380,644, titled “Mechanically Pumped System for Direct Control of Two-Phase Isothermal Evaporation”, first named inventor: Eugene Jansen. The entirety of each of these applications is incorporated herein by reference. 
     BACKGROUND 
     Conventional methods of rejecting heat from a refrigerant or cooling system, e.g., vapor compression systems or phase change cooling system, requires sizing the heat-rejecting component(s), e.g., the condenser and fans, for a maximum design heat load at a maximum design ambient temperature. However, many heat loads may operate on a cycle wherein the maximum heat load occurs during only a portion of that cycle. Additionally, the maximum design ambient temperature likely is not always present. Some heat-transfer systems employ complex, variable-frequency-drive compressors to facilitate the heat-rejection capacity control that are expensive and frequently operate the compressor away from its peak efficiency. Sizing the heat exchanger system for the maximum heat load at continuous duty cycle in the maximum expected ambient air condition results in an oversized, overweight, and overpowered condensing unit for those portions of the duty cycle that are neither at, nor near, the most limiting design conditions. 
     SUMMARY 
     According to some aspects of the present disclosure, a heat transfer system may include a primary fluid and a primary fluid flow path. The primary fluid may be disposed in the primary fluid flow path. The primary fluid flow path may include a heat exchanger with an inlet and an outlet, which transfers heat into the primary fluid; a compressor, with a compressor inlet and a compressor outlet. The compressor inlet may be downstream of and coupled to the heat exchanger outlet by a heat-exchanger-compressor conduit. The flow path may include a condenser, with a condenser inlet and a condenser outlet. The condenser inlet may be downstream of and coupled to the compressor outlet by a compressor-condenser conduit. The condenser may transfer heat out of the primary fluid. The flow path may also include a thermal energy storage (TES) section. The TES section may include an inlet and an outlet. The TES section inlet may be downstream of and coupled to the condenser outlet by a condenser-TES-section conduit. The TES-section outlet may be upstream of and coupled to the heat exchanger inlet by a TES-section-heat-exchanger conduit. The TES-section may include a TES unit having an inlet and outlet. The TES unit inlet may be downstream of and coupled to the TES section inlet by a TES-section-TES-unit-inlet conduit and the TES unit outlet may be upstream of and coupled to the TES Section outlet by a TES-unit-TES-section-outlet conduit. The TES-section may also include a first pressure regulating valve downstream of the TES unit; and a second pressure regulating valve upstream of the first pressure regulating valve and downstream of the condenser. The second pressure regulating valve may maintain the primary fluid at the condenser outlet at a first state when the heat transferred into a portion of the primary fluid by the heat exchanger may be equal to or less than the heat transferred out of the portion of the primary fluid by the condenser. The first pressure regulating valve may maintain the primary fluid at the TES unit outlet at the first state when the heat transferred into a portion of the primary fluid by the heat exchanger may be greater than the heat transferred out of the portion of the primary fluid by the condenser. The TES section may maintain the primary fluid at the TES section outlet as a liquid-vapor mixture. 
     In some embodiments, the first state may be at saturation pressure. In some embodiments, the first state may be a subcooled liquid. In some embodiments, the first state may be a saturated fluid. In some embodiments, the heat exchanger may be an evaporator. In some embodiments, the TES unit comprises a material selected from the group consisting of a phase change material, chilled water, chilled coolant, or two-phase mixture of water and ice. Some embodiments may include a bypass valve upstream of TES unit and downstream of the condenser. In some embodiments, the bypass valve may direct the primary fluid to the second pressure regulating valve in a first position or to the TES unit in a second position. Some embodiments may include a TES cooling fluid conduit coupled to the TES-section-heat-exchanger conduit and the bypass valve, wherein the bypass valve may be a four-way valve. In some embodiments, the bypass valve may be in parallel with the second pressure regulating valve. In some embodiments, the second pressure regulating valve maintains the primary fluid at the TES unit inlet as a liquid-vapor mixture. Same embodiments may include a first bypass valve downstream of the TES unit and coupled in parallel with the first pressure regulating valve; and, a second bypass valve upstream of the TES unit and coupled in parallel with the second pressure regulating valve. In some embodiments, the second pressure regulating valve may be upstream of the TES unit. In some embodiments, the TES-section-heat-exchanger conduit comprises an accumulator and a liquid pump, and the heat-exchanger-compressor conduit comprises the accumulator. Some embodiments may include a TES cooling fluid conduit coupling an outlet of the liquid pump and a four-way valve upstream of TES unit and downstream of the condenser. 
     According to some aspects of the present disclosure, a heat transfer system with a closed fluid flowpath may include in a direction of fluid flow a heat source, a compressor, a condenser, a first bypass valve in a first mode or a first pressure regulating valve in a second mode, a thermal energy storage (TES) unit, and a second pressure regulating valve in the first mode or a second bypass valve in the second mode. The TES unit may be a heat sink in the first mode and the TES unit may be a heat source or heat neutral in a second mode. 
     In some embodiments, the first pressure regulating valve may be a diaphragm-style back pressure regulating valve. In some embodiments, at least one of the first pressure regulating and the second pressure regulating valve may be a pneumatically controlled valve. 
     According to some aspects of the present disclosure, a heat transfer system with a fluid flowpath may include in a direction of fluid flow a heat source, a compressor, a condenser, a first input of a four-way valve, a thermal energy storage (TES) unit in a first mode or a first pressure regulating valve in a second mode, and a second pressure regulating valve. The TES unit may be a heat sink in the first mode and the TES unit may be a heat source or heat neutral in a second mode. 
     In some embodiments, the TES unit may include a material selected from the group consisting of a phase change material, chilled water, chilled coolant, or two-phase mixture of water and ice. In some embodiments, the heat source may be an evaporator. Some embodiments may include an accumulator; and a pump. Some embodiments may include a second flow path which itself may include the pump, a second input of the four-way valve, the TES unit, the second pressure regulating valve, and the accumulator. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following will be apparent from elements of the figures, which are provided for illustrative purposes. 
         FIG. 1  is a graph of various heat loads with respect to time. 
         FIG. 2  illustrates a heat transfer system in accordance with some embodiments. 
         FIG. 3  is a graph of a heat load with respect to time. 
         FIG. 4  illustrates a heat transfer system in accordance with some embodiments. 
         FIG. 5  illustrates a heat transfer system in accordance with some embodiments. 
         FIG. 6  illustrates a heat transfer system in accordance with some embodiments. 
         FIG. 7  illustrates a heat transfer system in accordance with some embodiments. 
     
    
    
     The present application discloses illustrative (i.e., example) embodiments. The claimed inventions are not limited to the illustrative embodiments. Therefore, many implementations of the claims will be different than the illustrative embodiments. Various modifications can be made to the claimed inventions without departing from the spirit and scope of the disclosure. The claims are intended to cover implementations with such modifications. 
     DETAILED DESCRIPTION 
     For the purposes of promoting an understanding of the principles of the disclosure, reference will now be made to a number of illustrative embodiments in the drawings and specific language will be used to describe the same. 
     Conventional methods of rejecting heat from a heat transfer system, e.g., a refrigerant system, requires sizing the heat-rejecting component(s), e.g., a condenser, fans, etc., for a maximum design ambient temperature and maximum design heat loads. Such methods may work well for a heat load with little variation, such as heat load  101  shown in  FIG. 1 . Heat load  101  may be, for example, a building in which the variation in heat load  101  is driven by daily fluctuations in ambient temperature and building use. However, this design philosophy results in heat-rejecting components, e.g., condensers and/or fans, that may be much larger than what is required for average ambient temperatures and/or average loads, particularly for systems having widely varying and/or intermittent loads such as heat load  103 . Heat load  103  may have a low, steady state heat load that is periodically interrupted by short periods of significantly higher heat loads. Additionally, the temperature of cooled load, or the temperature at which the load is to be maintained, may be different during the low, steady state heat load and the higher heat load. A system designed to accommodate heat load  103  typically would size the heat-rejecting components, like the condenser, to handle the larger, less frequent load, resulting in condenser that is much larger and/or fans that are required to provide significantly more airflow (and power required to drive those fans) than what is required to support the lower, average load. These system designs occupy more volume, weigh more, may require more power for transfer of cooling fluid or air, and may respond more slowly during transients. 
     In accordance with some embodiments, a heat transfer system  200  is illustrated in  FIG. 2 . The system  200  may comprise a primary fluid flow path  202  having a primary fluid disposed therein. The primary fluid flow path  202  may comprise various components configured to transfer the heat from one location and dispose of it into another. These other components may comprise heat exchanger  204 , compressor  206 , condenser  208 , and thermal energy storage (TES) section  210 . These components may be arranged in a loop such that each subsequent component, as listed in the order above, being located downstream of the prior components and the effluent of the TES section  210  being returned to the heat exchanger  204  to complete the loop. 
     Each of above components forming the primary fluid flow path  202  may be coupled to one another via one or more conduits. For example, the outlet  260  of heat exchanger  204  may be coupled to the inlet  262  of compressor  206  via the heat-exchanger-compressor conduit  264 ; the outlet  266  of compressor  206  may be coupled to the inlet  268  of condenser  208  by the compressor-condenser conduit  270 ; the outlet  272  of condenser  208  may be coupled to the inlet  274  of TES section  210  by condenser-TES-section conduit  276 ; and, outlet  278  of TES section  210  may be coupled to the inlet  280  of heat exchanger  204  by a TES-section-heat-exchanger conduit  282 . 
     Primary fluid flow path  202  may comprise additional components and/or conduits, some of which are described herein. The primary fluid flow path  202  may form a closed fluid flow path, meaning that the system  200  is designed such that the primary fluid does not intentionally enter or leave the primary fluid flow path  202  during normal operation. Being characterized as closed does not prohibit, however, primary fluid from being added to or removed from the primary fluid flow path  202  to make up for leaks, change of the primary fluid after fluid degradation, or for some other maintenance or repair procedure. 
     The primary fluid disposed with the primary fluid flow path  202  can be any appropriate fluid, vapor or liquid, capable of achieving the desired heat transfer. For example, the primary fluid may be water or a refrigerant. The particular fluid for system  200  can be dependent upon the heat load and the temperature of the environments/systems that transfer heat into or out of the system  200 . 
     Heat exchanger  204  may be of suitable type for transferring heat  212  into the primary fluid, which runs in the cold-side channels (or tubes or other appropriate geometry) of heat exchanger  204 . Heat exchanger  204  may be a heat source or load. The hot-side channels may be filled with fluid, e.g., water or air, from the environment/system to be cooled. Heat exchanger  204  may be a parallel-flow, cross-flow, multi-pass-flow, or counter-flow heat exchanger. In some embodiments, heat exchanger  204  is an evaporator that evaporates a portion or all of the primary fluid flowing therein. In some embodiments, heat exchanger  204  may comprise a series of conduits thermally coupled to a heat source or load that is not a fluid. For example, the conduits of heat exchanger  204  may be placed in thermal proximity, contact, or coupling with a solid structure that produces heat such that this heat is transferred into and removed by the primary fluid. 
     The heat transfer  212  into the primary fluid in heat exchanger  204  may be a variable load such as heat load  103  as shown in  FIG. 1 . Another example of a variable load  300  is illustrated in  FIG. 3 . As can be seen, heat load  300  is above its average heat load  303  for only a portion of time. A typical heat transfer system would be sized based on the peak heat load  305 . This design results in a condenser, compressor, and/or fans that are oversized for all but the peak heat load  305 . 
     Compressor  206  raises the pressure of the primary fluid. This increase in pressure may be used to provide the workflow required to circulate the primary fluid within the primary fluid flowpath  202 . Raising the pressure of the primary fluid may also raise the temperature of the primary fluid, thereby allowing heat to be rejected from the primary fluid in the condenser  208 . In some embodiments, compressor  206  may be a pump configured to raise the pressure of liquid, such as in an absorption system (see  FIG. 7 , discussed below). 
     Condenser  208  receives the higher-temperature/pressure primary fluid from the compressor  206 . Condenser  208  may be a heat exchanger that rejects heat  214  from the primary fluid to a heat sink which may be, e.g., the ambient environment. Condenser  208  may be a parallel-flow, counter-flow, multi-pass-flow, or cross-flow heat exchanger. The primary fluid may run in the hot-side channels of condenser  208 . The cold-side channels of condenser  208  may be filled with a fluid from the heat sink, e.g., ambient air. 
     Condenser  208  may be sized such that the condenser  208  may be insufficient to condense and/or sub cool all of the primary fluid flowing therethrough when heat input  212  and compressor  206  power and heat input is sufficiently larger than heat-out  214  (a person of ordinary skill will recognize that the energy inputted into system  200  must be rejected at some point in order for the system  200  to continue effective operation; as such, heat input  212  can be considered as including additional sources of energy (from, e.g., pump work) even if not expressly stated herein). To accommodate this intermittent, maximum load, system  200  may comprise a TES section  210  to which heat may be temporarily rejected. Once the heat input  212  and compressor  206  power and heat input drops below a particular rate relative to rate of heat output  214  of condenser  208 , condenser  208  may condense and/or sub cool the primary fluid. This primary fluid is then used to cool, or “recharge,” the thermal capacity of TES section  210 . 
     With reference to  FIG. 3 , if the condenser  208  is sized to accommodate the average heat load  303 , a heat input above the average  303 , as represented by heat-excess area  307 , will prevent the condenser from condensing and/or sub cooling the primary fluid. During this period, the supplemental heat capacity of TES section  210  is used to make up for the deficiency of the condenser  208 . When the heat load  300  is less than the average heat load  303 , as represented by the area  309  in  FIG. 3 , the condenser  208  has capacity to condense and/or sub cool a portion or all of the primary fluid that may be subsequently used to recharge the TES section  210  (and, in particular, the TES unit  220  as described below) while concurrently rejecting the heat from heat load  212 . 
     In some embodiments, condenser  208  may comprise a force ventilation unit (not shown), such as a fan, that increases the flow rate of the ambient environment fluid over condenser  208 . The “sizing” of the condenser  208  may factor in the addition of the forced ventilation unit. 
     To provide this thermal capacity, TES section  210  may comprise several components, including pressure regulating valve  216 , bypass valve  218 , TES unit  220 , pressure regulating valve  222 , and bypass valve  224 . 
     TES unit  220  has an inlet  226  and outlet  228 . Inlet  226  of TES unit  220  is downstream of and coupled to TES section inlet  274  by TES-section-TES-unit-inlet conduit  284 . Outlet  228  of TES unit  220  is upstream of and coupled to TES section outlet  278  by TES-section-TES-unit-outlet conduit  286 . As shown in  FIG. 2  and other figures, the conduits coupling the TES unit  220  to the inlet and/or outlet of the TES section  210  may have various components disposed therein and/or coupled in parallel with all or a portion of the conduits. 
     TES unit  220  provides a secondary heat sink for the primary fluid disposed in the primary fluid flow path  202 . When the heat input  212  from heat exchanger  204  and compressor  206  power and heat input is sufficiently large such that the heat output  214  of condenser  208  cannot fully condense the primary fluid within the condenser  208 , TES unit  220  provides a supplemental heat sink that can condense the remaining vapor of the primary fluid. While heat can be rejected to TES unit  220  to complete this condensing, TES unit  220  may have a limited thermal capacity such that only a limited amount of heat can be rejected to TES unit  220 . For an intermittent heat load, the thermal capacity of TES unit  220  can be sized to match the difference between the average heat load and the maximum heat load over a designed period of time. After the thermal capacity of the TES unit  220  has been exceeded, TES unit  220  must be recharge for subsequent heat loads that exceed the thermal output capacity of condenser  208 . 
     Examples of materials that may form TES unit  220  include phase change materials, chilled water, chilled coolant, two-phase mixtures such as water and ice, or other suitable material. 
     TES section  210  may further comprise pressure regulating valve  216 , bypass valve  218 , pressure regulating valve  222 , and bypass valve  224 . These components may aid in using TES unit  220  as a heat sink and providing primary fluid to TES unit  220  at a temperature that recharges the thermal capacity of TES unit  220 . 
     During steady-state periods of high heat loads for which the condenser  208  is unable to fully condense the primary fluid, bypass valve  218  is open and bypass valve  224  is shut. Primary fluid flowing through valve  218  bypasses pressure regulating valve  216 . With bypass valve  224  being closed, pressure regulating valve  222  maintains the pressure of the primary fluid upstream of pressure regulating valve  222  at saturation pressure through both the condenser  208  and TES unit  220 . Primary fluid flowing in condenser  208  is partially condensed, and flows through bypass valve  218  to TES unit  220  that completes the condensing process. TES unit  220  may sub cool the primary fluid. The liquid primary fluid is then expanded across pressure regulating valve  222 , dropping the primary fluid temperature prior to the fluid returning to heat exchanger  204 . 
     During the transition from the lower heat loads to the above stated steady state high heat load operation, pressure regulating valve  216  will regulate the pressure in condenser  208  and pressure regulating valve  222  will regulate pressure in the TES unit  220  independently from one another. Pressure regulating valve  216  may be fully open when bypass valve  218  is fully opened. After pressure regulating valve  216  is fully open, pressure regulating valve  222  will regulate the pressure in the condenser  208  and TES unit  220 . Bypass valve  224  may be shut during this operation. The pressure of the primary fluid in the TES unit  220  may be set to maximize heat rejection, target a specific heat duty, or provide a specific amount of sub-cooling at the outlet of TES unit  220 . The pressure within the condenser  208  may be set to maximize condenser heat rejection, keep the compressor  206  operational, or provide a specified sub-cool at the outlet of the condenser  208 . 
     During operations in which the condenser  208  is able to fully condense, and possibly sub-cool, the primary fluid, the TES unit may be recharge at a maximum rate by operating the system such that bypass valve  218  is shut and bypass valve  224  is opened. With valve  218  shut, pressure regulating valve  216  maintains the primary fluid pressure in the condenser  208  at saturation pressure. The primary fluid is fully condensed, and possibly sub cooled, by the condenser  208 . Primary fluid is expanded across pressure regulating valve  216 , dropping the temperature of the primary fluid as its heat energy is used to vaporize all or a portion of the primary fluid. The lower temperature primary fluid flows through TES unit  220 , extracting heat from TES unit  220  when TES unit  220  is at a higher temperature than the primary fluid. This heat transfer recharges the thermal capacity of the TES unit. The primary fluid mixture then flows through valve  224 , bypassing pressure regulating valve  222 , on its way to heat exchanger  204  as a vapor or a vapor-liquid mixture. 
     During a transition from operations during which TES unit  220  is required to supplement condenser  208  to operations in which the TES unit is recharged at the maximum rate, pressure regulating valve  222  may regulate the pressure of the TES unit  220  independently of the pressure in condenser  208 . Pressure regulating valve  222  may being to open during this transition. When pressure regulating valve  222  is fully open bypass valve  224  is also fully open. Bypass valve  218  is shut for the duration such that pressure regulating valve  216  is able to regulate the pressure within condenser  208 . 
     Condenser  208  may also be configured to operate in different modes, e.g., with or without forced ventilation. The condenser  208  may be sized such that the average heat load  212  and the compressor  206  power and heat transferred into the primary fluid exceeds the ability of the condenser  208  to reject heat out  214  during a mode where no forced ventilation is provided. TES unit  220  may provide the additional heat rejection capacity during such a mode of operation. 
     Pressure regulating valves  216  and  222  may be backpressure regulating valves. Bypass valves  218  and  224  may be solenoid valves that are operated based on the parameters of the primary fluid (e.g., temperature and pressure, advanced logic control). 
     Each pressure regulating valve  216  and  222  and its associated bypass valve  218  and  224 , respectively, may be replaced with a single, accurate, fast-acting control valve. For example, the replacement valve for pressure regulating valve  222  and bypass  224  may be a diaphragm back pressure regulating valve or a pneumatically driven valve. This replacement valve should be able to handle the primary fluid flow in all states (i.e., vapor, liquid) and accurately control the sub cooling of the primary fluid. These features are important if the compressor  206  and condenser  208  cannot keep up with the rate of evaporation of the TES unit  220  at low saturation pressures/temperatures (i.e., the temperature of refrigerant required to cool the TES may not be maintained). By using downstream control of the cooling of the primary fluid at the TES unit  220 , the saturation pressure and temperature of the TES unit  220  can be regulated thereby regulating the heat transfer rate at the TES unit  220  without impacting the lower-pressure primary fluid downstream of the TES section  210 . 
     Embodiments in which a bypass valve is connected in parallel with a pressure regulating valve may avoid the pressure drop that may occur across a fully open pressure regulating valve. 
     As another example, the replacement valve for pressure regulating valve  216  and bypass valve  218  may be a diaphragm-style back-pressure regulating valve, typically pneumatically, spring or electronically controlled valve. This replacement valve should be accurate and fast-acting. 
     In accordance with some embodiments, a diagram of a heat transfer system  400  is provided in  FIG. 4 . Heat transfer system  400  is comprised of many of the same components performing the same functions as those described herein elsewhere. The primary differences between heat transfer systems  200  and  400  are located within TES sections  210  and  410 . In TES section  410 , four-way valves  430  and  486  are disposed in TES section  410  to bypass, utilize, or cool TES unit  220  using conduits  484  and  486  as well as TES cooling fluid conduit  432 . 
     During operations in which the heat load input  212  and compressor  206  heat and power input can be accommodated by the heat output  214  of condenser  208 , four-way valve  430  is positioned to direct the liquid, possibly sub cooled, primary fluid from the effluent of condenser  208  to pressure regulating valve  222  via conduit  484  and bypass valve  486 . Like above, pressure regulating valve  222  maintains the pressure in condenser  208  at saturation conditions to ensure that the primary fluid is condensed and/or sub-cooled in condenser  208 . Primary fluid is expanded across pressure regulating valve  222 . A portion of the expanded primary fluid is directed through TES cooling fluid conduit  432  and bypass valve  486  to TES unit  220 , thereby providing a supply of chilled primary fluid to cool and recharge TES unit  220 . After cooling TES unit  220 , the fluid flows through bypass valve  430  to the heat-exchanger-compressor conduit  264  via TES cooling fluid conduit  432 . 
     The portion of fluid that does not flow through TES cooling fluid conduit is provided to the inlet  280  of heat exchanger  204  via the TES-section-heat-exchanger conduit  282 . 
     During operations with a heat input  212  plus compressor  206  power and heat input that exceeds the capacity of condenser  208  to fully condense the primary fluid, four-way valve  430  is positioned to route the effluent of condenser  208  to TES unit  220  via conduit  486 . The TES unit  220  completes the condensing and/or sub cooling of the primary fluid. Fluid is then directed to the pressure regulating valve  222  via bypass valve  486 . Pressure regulating valve  222  maintains the upstream primary fluid pressure at conditions necessary to promote the required heat transfer. The primary fluid is expanded across pressure regulating valve  222  and provided back to heat exchanger  204 . Four-way valves  430  and/or  486  are positioned to prevent the flow of primary fluid in the TES cooling fluid conduit  432  and conduit  484  during this mode of operation. 
     In some embodiments, TES cooling fluid conduit  432  is connected between a portion of the TES-section-heat-exchanger conduit  282  and four-way valve  486 . 
     While some embodiments described here incorporated a TES section into vapor compression cycle refrigeration system, it should be understood that the advantages of incorporating a TES section can be enjoyed in other refrigeration systems, with the TES section supplementing the heat rejecting components of those other systems. As such, nothing herein should be construed as limiting the incorporation of a TES section to only a vapor compression system. 
     An example of another system is provided for in  FIG. 5 .  FIG. 5  illustrate a heat transfer system  500  in accordance with some embodiments. Heat transfer system  500  may comprise similar components performing similar functions as described elsewhere herein. It should be understood that many of these components are omitted from  FIG. 5  for ease of reading. 
     In addition to components described with respect to other systems, heat transfer system further comprises an accumulator  534  and a pump  536 . The additional components are combined with the illustrated vapor compression system to form what is called a liquid overfeed system. Further details and embodiments of liquid overfeed systems are provided for in the concurrently filed and related U.S. application Ser. No. 16/380,644 entitled “MECHANICALLY PUMPED SYSTEM FOR DIRECT CONTROL OF TWO-PHASE ISOTHERMAL EVAPORATION”, first named inventor: Eugene Jansen. The entirety of which is hereby incorporated by reference. 
     Accumulator  534  is located between the effluent of TES section  510  (which may be TES section  210  and/or  410 ) and the suction of compressor  206 . The accumulator  534  provides several functions, including at least providing a surge volume of refrigerant for supply to heat exchanger  204 , providing pump head for pump  536 , and separating the vapor/liquid mixture from the effluent of both the TES section  510  and evaporator  204 . As such, accumulator  534  has at least two inputs and two outputs. The inputs are from the effluents of the TES section  510  and evaporator  204 . The two outputs are from vapor supplied to the compressor  206  and the fluid supplied to pump  536 . 
     For embodiments that utilize a TES cooling fluid conduit  532 , the conduit may be placed downstream of pump  536 , thereby coupling the outlet of pump  536  and a valve in the TES section  510 , e.g., input of four-way valve  486  of TES section  410 . Other locations may also serve as the initiating point of TES cooling fluid conduit  532 . 
     In accordance with some embodiments, a heat transfer system  600  is illustrated in  FIG. 6 . Heat transfer system  600  is comprised of many of the same components performing the same functions as those described elsewhere herein. It should be understood that several components of heat transfer system  600  have been omitted for clarity. The primary differences between heat transfer systems  200 ,  400  and  600  are located within TES sections  210 ,  410  and  610 . In TES section  610 , a four-way valve  688  is disposed between the upstream side of both pressure regulating valve  216  and TES unit  220  and the outlet  272  of the condenser  208 . Downstream of both pressure regulating valve  216  and TES unit  220  is pressure regulating valve  222 . Unlike heat transfer system  200  and  400 , pressure regulating valve  216  is not upstream of TES unit  220  in system  600 . Additionally, TES section  610  comprises a TES unit cooling fluid conduit  932  that is located downstream of pressure regulating valve  222  and fluidically couples this location to an inlet of four-way valve  688 . For example, TES unit cooling fluid conduit  932  may be coupled to the outlet of pump  536  as shown in  FIG. 5  such that accumulator  534  is located within TES-section-heat-exchanger conduit  282  between the outlet  278  and the branch-off point of TES unit cooling fluid conduit  932 . 
     During operations in which the heat load input  212  plus compressor  206  power and heat input can be accommodated by the heat output  214  of condenser  208 , four-way valve  688  is positioned to direct the liquid, possibly sub cooled, primary fluid from the effluent of condenser  208  to pressure regulating valve  216  via conduit  690 . Like above, pressure regulating valve  216  maintains the pressure in condenser  208  at saturation conditions to ensure that the primary fluid is condensed in condenser  208 . Primary fluid is expanded across pressure regulating valve  216  and then flows to pressure regulating valve  222 , which is fully open and is not maintaining upstream primary fluid pressure. A portion of the expanded primary fluid may be directed through TES cooling fluid conduit  932  and the four-way valve  688  to TES unit  220 , thereby providing a supply of chilled primary fluid to cool and recharge TES unit  220 . A pump, e.g. pump  536 , may supply the pump work require to drive the primary fluid through TES cooling fluid conduit  932 . The outlet  278  of TES section  610  is coupled to the accumulator  534  at a point upstream of the branch-off of TES cooling fluid conduit  932 . 
     During operations with a heat input  212  that exceeds the capacity of condenser  208  to fully condense the primary fluid, four-way valve  688  is positioned to route the effluent of condenser  208  to TES unit  220  via conduit  692 , bypassing pressure regulating valve  216 . The TES unit  220  completes the condensing and/or sub cooling of the primary fluid. Pressure regulating valve  222  maintains the upstream primary fluid pressure at conditions necessary to transfer the required heat. The primary fluid is expanded across pressure regulating valve  222  and provided back to heat exchanger  204 . Four-way valve  688  is positioned to prevent the flow of primary fluid in the TES cooling fluid conduit  932  during this mode of operation. 
     In accordance with some embodiments, a heat transfer system  700  is illustrated in  FIG. 7 . System  700  may comprise many of the same components that perform the same functions as described above. System  700  differs from those disclosed in that it does not contain a vapor compression loop. Rather, system  700  is an adsorption system that comprises absorber  794 , pump  796 , generator  798 , and valve  7100 . Primary fluid from heat exchanger  204  is provided to absorber  794  wherein the primary fluid is absorbed into an absorbent while heat is rejected. The absorbent/primary fluid mixture is sent via pump  796  to generator  798 . In Generator  798 , heat is provided to the generator, thereby releasing the absorbed primary fluid for flow to condenser  208 , TES section  210 , and then returning to heat exchanger  204 . Absorbent is allowed to return to the absorbed  794  via valve  7100 , which also functions to maintain a pressure differential between generator  798  and absorber  794 . 
     While the above illustrated system  700  utilizes TES section  210 , it should be understood that this absorption system may also utilize TES section  410 ,  510 , or  610  and their manner of interfacing with the rest of the systems disclosed above. 
     Although examples are illustrated and described herein, embodiments are nevertheless not limited to the details shown, since various modifications and structural changes may be made therein by those of ordinary skill within the scope and range of equivalents of the claims. A person of ordinary skill will recognize that the particular valves disclosed herein may be replaced with other, functionally equivalent arrangements. For example, the herein disclosed 4-way valves may be replaced with combinations of 3-way valves, 2-way valves, or both.