Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
  • F28D20/00—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00
  • F28D20/02—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00 using latent heat
  • F28D20/021—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00 using latent heat the latent heat storage material and the heat-exchanging means being enclosed in one container
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/14—Thermal energy storage

Definitions

• Embodiments of the present disclosure are directed towards methods of operating a heat exchanger, more specifically, embodiments are directed towards methods of operating a heat exchanger that include: transferring heat from a liquid phase change material to a heat transfer fluid through a heat exchanger surface; forming a solid on the heat exchanger surface, wherein the solid is formed from the liquid phase change material; and heating the heat exchanger surface to form a liquid portion from the solid.
• a heat exchanger is an apparatus which transfers heat from one medium to another medium. For instance, heat may be transferred from one fluid to another fluid.
• the heat may be transferred by conduction through a material that separates the mediums being used.
• Heat exchangers may be utilized for a number of various applications
• Methods of operating a heat exchanger are disclosed herein. Methods disclosed herein can include: transferring heat from a liquid phase change material to a heat transfer fluid through a heat exchanger surface; forming a solid on the heat exchanger surface, wherein the solid is formed from the liquid phase change material; and heating the heat exchanger surface to form a liquid portion from the solid, as discussed further herein.
• Embodiments of the present disclosure can provide an improved heat power output, e.g., an improved heat flow. For instance, as heat is transferred from a liquid, e.g., molten, phase change material to a heat transfer fluid through a heat exchanger surface, a portion of the liquid phase change material may be cooled such that a solid is formed on the heat exchanger surface.
• the presence of the solid on the heat exchanger surface can reduce the heat power output of the heat exchanger, as the solid phase change material has lower thermal conductivity relative to a material of the heat exchanger, e.g., a heat exchanger surface; because of the presence of the solid on the heat exchanger surface heat exchange from the liquid phase change material to the heat exchanger surface is reduced.
• the heat exchanger 102 includes a heat exchanger material 104.
• the heat exchanger material 104 can separate mediums being utilized with the heat exchanger 102.
• the heat exchanger material 104 is thermally conductive. Heat may be transferred by conduction through the heat exchanger material 104, e.g., from a first medium to a second medium.
• Examples of the heat exchanger material 104 include aluminum, aluminum-brass, brass, carbon steel, carbon-moly, chrome-moly steel, copper, cupro- nickel, Inconel, Monel, nickel, stainless steel, titanium, and combinations thereof, among others.
• the heat exchanger material 104 may be electrically conductive.
• the heat exchanger material 104 can have a thickness 106.
• the thickness is
• the thickness 106 may have different values, e.g., for different applications.
• the thickness may have a value from 0.01 cm to 25.0 cm. All individual values and subranges from 0.01 cm to 25.0 cm are included; for example, the thickness may have a value from a lower limit of 0.01, 0.05, 0.1, or 0.2 cm to an upper limit of 25.0, 22.5, or 20.0 cm.
• the thickness 106 may have a single particular value throughout the heat exchanger material 104, or the thickness 106 may have a plurality of particular values throughout the heat exchanger material 104.
• the heat exchange material 104 may include one material or a number of different materials.
• the first channel material 112, the first heat exchanger surface 108, and additional first channel materials not illustrated in Figure 1 can form a first channel 116.
• the second channel material 114, the second heat exchanger surface 110, and additional second channel materials not illustrated in Figure 1 can form a second channel 118.
• the first channel 116 and the second channel 118 can each independently be utilized as fluid conduits and/or fluid reservoirs. Other portions of the heat exchanger 102, not illustrated in Figure 1, can provide fluids to the first channel 116 and the second channel 118.
• the first channel 116 and the second channel 118 can each independently have a number of differing volumes, e.g., based upon various heat exchanger applications.
• the heat exchanger material 104 can separate mediums, e.g., fluids, being utilized with the heat exchanger 102.
• the separated mediums can include a phase change material and a heat transfer fluid.
• heat can be exchanged from a liquid phase change material to a heat transfer fluid via a heat exchanger surface.
• a phase change material refers to a material that transitions from a first state, e.g., a liquid state, to a second state, e.g., a solid state, as heat is transferred from the phase change material.
• a first state e.g., a liquid state
• a second state e.g., a solid state
• the phase change material e.g., in the liquid state, may be utilized to store thermal energy.
• the liquid phase change material may be at a temperature from -50 °C to
• the liquid phase change material be from a lower limit of -50 °C, -25 °C, 0 °C, 25 °C 50 °C, 75 °C, 100 °C, 125 °C, 150 °C, 160 °C, or 175 °C to an upper limit of 600 °C, 550 °C, 500 °C, 450 °C, 400 °C, 385 °C, or 375 °C.
• heat transfer fluid refers to a material that receives heat from the phase change material.
• the heat transfer fluid can transport heat, e.g., heat received from the phase change material, to another component, such as an electrical producing process, among others.
• the heat transfer fluid may be a liquid, a gas, or a combination thereof.
• Examples of heat transfer fluids include air, water, silicone fluids, inhibited glycol-based fluids, mineral oils, among others.
• examples of the heat transfer fluid include fluids available under the tradename DOWTHERMTM, available from the Dow Chemical Company.
• the heat transfer fluid may be a phase change material.
• the heat transfer fluid may be a liquid that phase changes to a gas as heat is received from the phase change material discussed above.
• Embodiments of the present disclosure provide that the liquid phase change material is utilized in either the first channel 116 or the second channel 118, while the heat transfer fluid is utilized in the channel not containing the liquid phase change material.
• the liquid phase change material and the heat transfer fluid are located on opposite sides of the heat exchanger material 104, heat can be transferred from the liquid phase change material to the heat transfer fluid by conduction through the heat exchanger material 104.
• the heat transfer fluid may be utilized continuously, e.g., the heat transfer fluid may flow.
• Flow of the heat transfer fluid may be counter-current, co-current, or cross-current relative to a flow of the liquid phase change material.
• the liquid phase change material is stagnant relative to a flow of the heat transfer fluid.
• all or a portion of the heat transfer fluid may phase change, e.g., evaporate, as the heat transfer fluid receives heat from the liquid phase change material.
• Flows of the heat transfer fluid may be different for various
• the liquid phase change material can cool, particularly portions of the liquid phase change material located near, e.g., adjacent to, the heat exchanger material 104. As the liquid phase change material cools, the liquid phase change material can transition to a solid phase.
• a solid formed from the phase change material can form on the first heat exchanger surface 108.
• a solid formed from the phase change material can form on the second heat exchanger surface 110.
• the presence of the solid on the heat exchanger surface can undesirably reduce the heat power output of the heat exchanger, as the solid phase change material has a lower thermal conductivity relative to the heat exchanger material 104, which may reduce convection between the liquid phase change material and the heat exchanger material 104.
• heating the heat exchanger surface to form a liquid portion from the solid includes providing a heated fluid to the channel that is opposite the channel having the solid phase change material formed on the heat exchanger surface. For instance, if the solid phase change material is formed on heat exchanger surface 108, the heated fluid may be provided to the channel 118. Similarly, if the solid phase change material is formed on heat exchanger surface 110, the heated fluid may be provided to the channel 116. Energy, provided by the heated fluid, can heat the heat exchanger material 104 and heat exchanger surfaces 108 and 110. Heat, provided from the heated fluid, can be transferred from the heat exchanger surface to the solid phase change material formed on the particular heat exchanger surface.
• the heated fluid may be the heat transfer fluid, where energy is provided to the heated fluid by other than the phase change material.
• the heated fluid is different than the heat transfer fluid. Examples of the heated fluid include air, silicone fluids, inhibited glycol-based fluids, mineral oils, among others.
• heating the heat exchanger surface to form a liquid portion from the solid includes providing a thermal conduction source to the heat exchanger surface.
• the thermal conduction source has more thermal energy, e.g., is at a higher temperature, than the heat exchanger material 104 and heat exchanger surfaces 108 and 110.
• a thermal conduction source can be coupled to heat exchanger material 104 and the thermal conduction source may be activated, e.g., switched on, to provide thermal energy to heat exchanger material 104 and heat exchanger surfaces 108 and 110.
• Energy, provided by the thermal conduction source can heat the heat exchanger material 104 and heat exchanger surfaces 108 and 110.
• Heat, provided from the thermal conduction source can be transferred from the heat exchanger surface to the solid phase change material formed on that particular heat exchanger surface.
• Various thermal conduction sources known in the art may be utilized.
• Heating the heat exchanger surface to form a liquid portion from the solid may be performed at predetermined intervals. For instance, heating the heat exchanger surface to form a liquid portion from the solid
• heating the heat exchanger surface to form a liquid portion from the solid may be performed according to a predetermined cycle.
• the heat exchanger surface may be heated, as discussed herein, e.g., by providing the electrical current to the heat exchanger material, multiple times with a time interval between heatings from 10 seconds to 48 hours. All individual values and subranges from 10 seconds to 48 hours are included; for example, heat exchanger surface may be heated with a time interval between heatings from a lower limit of 10 seconds, 30 seconds, 1 minute, 15 minutes, 30 minutes, or 60 minutes to an upper limit of 48 hours, 36 hours, 24 hours, or 12 hours.
• the heating following a heating cycle, i.e. heating the heat exchanger surface to form a liquid portion from the solid, the heating may be ceased for a time interval. After that time interval, heating the heat exchanger surface to form a liquid portion from the solid may resume.
• Heating the heat exchanger surface to form a liquid portion from the solid may be performed for a duration from 0.1 seconds to 1 hour. All individual values and subranges from 0.1 seconds to 1 hour are included; for example, the heat exchanger surface may be heated from a lower limit of 0.1 seconds, 0.5 seconds, 1 second, 5 seconds, 10 seconds, or 30 seconds to an upper limit of 1 hour, 0.9 hours, 0.8 hours, or 0.7 hours. For instance, following heating the heat exchanger surface to form a liquid portion from the solid being ceased for a time interval, as discussed herein, the heat exchanger surface may be heated for a duration from 1 second to 1 hour to form a liquid portion from the solid. The duration of heating the heat exchanger surface to form a liquid portion from the solid may be different for various applications.
• One or more embodiments of the present disclosure provide separating a portion of the solid from the heat exchanger surface. As mentioned, advantageously, portions of the solid may be separated from the heat exchanger surface to provide an improved heat power output.
• One or more embodiments of the present disclosure provide separating a portion of the solid from the heat exchanger surface utilizing a gravitational force. For instance, if the gravitational force is directed toward the first channel material 112 and the liquid phase change material is utilized in the first channel 116, then the solid phase change material may form on the first heat exchanger surface 108. As the first heat exchanger surface 108 is heated to form a liquid portion from the solid, the liquid portion intervening between the heat exchanger surface and the remaining solid can decouple, e.g. release, that remaining solid from the heat exchanger surface. Because the intervening liquid portion has decoupled the remaining solid, a portion of the solid may separate from the heat exchanger surface by the gravitational force. In other words, a portion of the solid may fall from the first heat exchanger surface 108 toward the first channel material 112.
• the heat exchanger surface may have various angles relative to the gravitational force.
• the heat exchanger surface may have an angle from 0° to 90° relative to the gravitational force. All individual values and subranges from 0° to 90° are included; for example, the heat exchanger surface may have an angle from a lower limit of 0°, 2°, 5°, or 10° to an upper limit of 90°, 85°, 80°, or 70° relative to the gravitational force.
• Separating a portion of the solid from the heat exchanger surface utilizing a gravitational force may occur for a duration from 0.01 seconds to 1 hour. All individual values and subranges from 0.01 seconds to 1 hour are included; for example, separating a portion of the solid from the heat exchanger surface utilizing a gravitational force may occur from a lower limit of 0.01 seconds, 0.1 seconds, 1 second, 5 seconds, 10 seconds, or 30 seconds to an upper limit of 1 hour, 0.7 hours, 0.5 hours, 0.4 hours, 0.2 hours, or 0.1 hours.
• a density of the solid phase change material can be greater than a density of the liquid phase change material.
• the density of the solid phase change material can be at least 3% greater, at least 5% greater, at least 7.5% greater, at least 10% greater, at least 12.5%) greater, or at least 15%> greater than the density of the liquid phase change material.
• Providing that the density of the solid phase change material is greater than the density of the liquid phase change material may be advantageous when separating a portion of the solid from the heat exchanger surface utilizing a gravitational force, for instance.
• One or more embodiments of the present disclosure provide separating a portion of the solid from the heat exchanger surface includes providing a flow of the liquid phase change material.
• heating the heat exchanger surface to form a liquid portion from the solid can provide the liquid portion intervening between the heat exchanger surface and the remaining solid, which can decouple that remaining solid from the heat exchanger surface. Because the intervening liquid portion has decoupled the remaining solid, providing a flow of the liquid phase change material can separate a portion of the solid from the heat exchanger surface. While not wishing to be bound to theory, it is believed that frictional forces between the flow of the liquid phase change material and the solid can provide separation, e.g., by application of a force, of a portion of the solid from the heat exchanger surface.
• the flow of the liquid phase change material may be an increased flow, as compared to preceding flow of the liquid phase change material having a relatively lesser flow rate and/or pressure.
• separating a portion of the solid from the heat exchanger surface includes providing a pressure difference, e.g. a first pressure and subsequently a second pressure, for the liquid phase change material.
• the liquid phase change material may be located in a particular portion of the channel 116, and a valve (not shown in Figure 1) in a restricting position, may restrict and/or stop flow of the liquid phase change material to provide a first pressure.
• heat from the liquid phase change material can be transferred to the heat transfer fluid through the heat exchanger surface, a solid can be formed on the heat exchanger surface, and the heat exchanger surface can be heated to form a liquid portion from the solid.
• a second pressure different than the first pressure may be provided, e.g., by opening the valve, relative to the restricting position.
• the first pressure may be greater than the second pressure. Due to the different pressures, the liquid phase change material may push a portion of the solid from the heat exchanger surface to provide an improved heat power output.
• Example 1 was performed as follows. For Example 1, a phase change material (LiNCb) was utilized. Liquid LiNCb was maintained at 257 °C in an insulated glass container by a 500 watt electrical heater. A stainless-steel plate (1.4571 stainless- steel; 170 mm x 65 mm x 1.5 mm) was fully submerged in the liquid LiNCb such that a plane including a longitudinal axis of the stainless-steel plate was parallel to a plane formed by the surface of the liquid LiNCb.
• LiNCb phase change material
• a heat transfer fluid (air, at a temperature of approximately 20 °C) was flowed through a channel (5 mm x 50 mm) in the stainless- steel plate at 30,000 liters/minute for approximately 10 minutes; the channel had an inlet and an outlet, each located at the top of the insulated glass container. Heat flowed from the liquid LiNCb to the stainless-steel plate to the heat transfer fluid, and visual inspection indicated that a solid material formed on the stainless-steel plate.
• Example 2 having Trials 1-3, was performed as follows.
• a phase change material LiNCb
• LiNCb phase change material
• liquid LiNCb had a density of 1.78 g/cm 3
• solid LiNCb had a density of 2.16 g/cm 3
• Liquid LiNCb was maintained at 257 °C in an insulated glass container by a 500 watt electrical heater.
• a dual channel apparatus was utilized.
• the dual channel apparatus included: a first and a second stainless-steel plate (each plate was 1.4571 stainless-steel; 170 mm x 65 mm x 1.5 mm); and a block (1.4571 stainless-steel of 152 mm x 65 mm x 11.5 mm) located between the first and a second stainless-steel plates.
• the first stainless-steel plate was separated (5mm) from the block to form a first channel
• the second stainless-steel plate was separated (5mm) from the block to form a second channel.
• Each channel was connected to an inlet and an outlet, both located at the top of the insulated glass container.
• the dual channel apparatus included an upper facing and a lower facing (each facing was 1.4571 stainless-steel) to seal the first and second channels; the upper and lower facings were separated from the first and second stainless-steel plates by ceramic gaskets to thermally and electrically isolate the facings from the plates.
• the dual channel apparatus was fully submerged in the liquid LiNCb such that a plane including a longitudinal axis of the first stainless-steel plate and a plane including a longitudinal axis of the second stainless-steel plate were perpendicular to a plane formed by the surface of the liquid LiNCb.
• a heat transfer fluid (air, at a temperature of approximately 340 °C) was flowed at 40 liters/minute to the heat apparatus to account for the heat losses at the top of the apparatus and maintain the energy balance. This was performed due to the apparatus components, such as piping and cables that exit the top of the apparatus and could not be insulated enough in order not to impact the Trials.
• the heat transfer fluid was reduced to a temperature of 90 °C and was flowed through each of the channels for approximately 12 minutes, which cooled the apparatus inlet pipe down to approximately 90 °C (measured via a temperature indication at the inlet of the channels to the plates).
• a battery which was able to supply approximately 2 volts, was coupled to the first stainless-steel plate by an electrical circuity including two plate connectors (each plate connector was 1.4571 stainless-steel) respectively attached near longitudinally opposite ends of the plate.
• Trial 1 The electrical circuit was switched on for approximately 149 seconds, following a time interval of approximately 271 seconds from the previous heating of the plate, to heat the first stainless-steel plate and the solid material formed on the plate. Visual inspection indicated that the solid material separated from the first stainless-steel plate and collected in the bottom of the insulated glass container. The electrical circuit was switched off. The second stainless-steel plate was not heated by the electrical circuit and the solid material that was formed on the second stainless-steel plate remained on the plate
• Q b Energy charged from LiNCb to the heat transfer fluid (air) during electrical heat up;
• a Trial e.g. Trial 1, which may be considered a cycle, is described as a LiNCb discharge time ti-to, a detachment of the solid material time t 2 -ti, and a time between detachment of the solid material and an electrical circuit switch off.
• heat energy Q a is transferred from the LiNCb material to the heat transfer fluid (air) via the first stainless-steel plate.
• the starting heat power q Q is decreasing to clover the time ti-to.
• the heat energy that was not charged to the heat transfer fluid (air) due to the buildup of the solid LiNCb material on the first stainless-steel plate is Qf.
• the electrical circuit is switched on and electrical energy Q e i is charged to the first stainless-steel plate during the time t 3 -ti.
• the electricity increases the temperature of the first stainless-steel plate surface where LiNCb is heated with the energy Qd.
• the electrical energy Q e i also heats up the heat transfer fluid (air) with Qc.
• the total energy charged to the heat transfer fluid (air) between t 3 and ti is Qb + Qc which means that it comes from both the electrical circuit Qc and from the LiNCb in
• Figure 2 is a graphical illustration 250 of data associated with an example of operating a heat exchanger in accordance with one or more embodiments of the present disclosure.
• Figure 2 illustrates data associated with Trials 1-3 of Example 2.
• Figure 2 includes measured voltages U2 in volts of the plate connectors over time on the left y axis and the energy transferred to the heat transfer fluid (air) q air in Watts on the right y axis, i.e. the heat power output.
• q air was determined utilizing the following Formula:
• Vair a i r volume flow passed to the first stainless-steel plate (m 3 /s);
• Pair density of air at 25 °C (kg/m 3 );
• cp air heat capacity of air at ( air out - d air in )l2 (J/kgK);
• Voltages (U2) of the plate connectors was determined as follows. A copper cable (127 mm 2 ) diameter was used to couple components of the dual channel apparatus, e.g., switches, fuses, battery and connectors, with the plate to the electrical circuit. Voltage measurements, during the Trials 1-3, were taken at several points between the copper cable and the plate to measure the voltages (U2). For the Trials, the plate connectors were to provide that there was no solid phase change material attached to the connectors when the plate was heated. For the Trials, the connectors were partially submerged in the liquid phase change material. As such, heat generated from the current that flowed through the connectors was also partially transferred to the liquid phase change material and therefore to the plate. This heat was included to the heat balance calculation.
• an estimated proportion of the heat from the connectors may also be transferred to the air above the liquid phase change material surface.
• voltages of the plate, the plate connectors, and the battery were determined at a temperature of approximately 23 °C.
• Electrical resistances of the plate (R piate) and R cable were calculated determined utilizing the following Formulas:
• U piate voltage at plate during operation of electrical circuit.
• U connector voltage at connector during operation of electrical circuit
• U battery voltage at battery during operation of electrical circuit.
• each "x" indicates a determined heat power output.
• Trial 1 had a relative maximum heat power output 252, which corresponded to a beginning of a cycle.
• the relative maximum heat power output 252 occurred when the first stainless- steel plate was essentially free of solid material formed thereon and the electricity was switched off.
• a decreasing heat power output region 254 was observed.
• decreasing heat power output region 254 was essentially an exponential decrease. The decreasing heat power output region 254 corresponded to formation of the solid material on the first stainless-steel plate.
• Trial 2 had a relative maximum heat power output 262, which
• the relative maximum heat power output 262 occurred when the first stainless-steel plate was essentially free of solid material formed thereon and the electricity was switched off, e.g., a portion of the solid material on the first stainless-steel plate formed in Trial 1 had been heated to form a liquid so that the remaining portion of the solid material separated from the first stainless-steel plate.
• a decreasing heat power output region 264 was observed as heat was transferred from the liquid LiNCb to the heat transfer fluid.
• decreasing heat power output region 264 was essentially an exponential decrease.
• the decreasing heat power output region 264 corresponded to formation of the solid material on the first stainless-steel plate.
• As the electrical circuit was switched on as indicated by voltage measurement 266, and solid material separated from the first stainless-steel plate, corresponding to time 268, and collected in the bottom of the insulated glass container, a desirable and increasing heat power output region 270 was observed.
• Trial 3 had a relative maximum heat power output 272, which
• the relative maximum heat power output 272 occurred when the first stainless-steel plate was essentially free of solid material formed thereon and the electricity was switched off, e.g., a portion of the solid material on the first stainless-steel plate formed in Trial 2 had been heated to form a liquid so that the remaining portion of the solid material separated from the first stainless-steel plate.
• a decreasing heat power output region 274 was observed as heat was transferred from the liquid LiNCb to the heat transfer fluid.
• decreasing heat power output region 274 was essentially an exponential decrease.
• the decreasing heat power output region 274 corresponded to formation of the solid material on the first stainless-steel plate.
• As the electrical circuit was switched on as indicated by voltage measurement 276, and solid material separated from the first stainless-steel plate, corresponding to time 278, and collected in the bottom of the insulated glass container, a desirable and increasing heat power output region 280 was observed.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
• Cooling Or The Like Of Electrical Apparatus (AREA)

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• 2018
  • 2018-03-08 US US16/492,702 patent/US20200049425A1/en not_active Abandoned
  • 2018-03-08 EP EP18712397.1A patent/EP3593074A1/en not_active Withdrawn
  • 2018-03-08 CN CN201880017217.XA patent/CN110402367A/zh active Pending
  • 2018-03-08 WO PCT/US2018/021473 patent/WO2018165379A1/en active Application Filing
• 2019
  • 2019-09-10 IL IL26924219A patent/IL269242A/en unknown

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