Microwave assisted hybrid solar vapor absorption refrigeration systems

Abstract

A microwave-assisted hybrid solar vapor absorption system that converts anergy into exergy and works sustainably without the intermittence associated with the single absorption vapor absorption systems. The heat required for the generator in a vapor absorption system is provided by preheating the water through solar collectors and by using the vehicle's waste heat in conjunction with solar heat, collecting the waste heat and the solar heat into circulating water or other thermal fluids like mineral oil through the vehicle's radiator, the vehicle's exhaust pipe, and a solar collector. By combining the waste heat and the solar heat, the system achieves the required generator temperature. By introducing dielectric heating and by differentially heating only the refrigerant fluid, and not the absorbent fluid, the required pressure for refrigeration is achieved, while allowing the absorbent fluid to remain significantly cooler than the refrigerant. This increases the Coefficient of Performance to 0.95.

Claims

1. A high exergy efficient hybrid solar vapor absorption system, comprising: an evaporator, the evaporator configured to cause evaporation of at least part of a refrigerant and absorbent solution, and cooling of the refrigerant and absorbent solution; a condenser in fluid communication with the evaporator, the condenser configured to decrease temperature of a gas contained therein thereby transitioning the gas into a liquid state; a thermal compressor in fluid communication with the evaporator and the condenser; wherein the refrigerant and absorbent solution flows throughout the high exergy efficient hybrid solar vapor absorption system including at least the evaporator, the condenser, and the thermal compressor; an expansion valve coupling together the evaporator and the condenser, wherein the expansion valve directs flow of the refrigerant and absorbent solution from the condenser to the evaporator: wherein the thermal compressor increases a pressure of the refrigerant and absorbent solution, thereby causing the refrigerant and absorbent solution to flow from the evaporator to the condenser; wherein the thermal compressor comprises: a generator (Q.sub.in) receiving solar energy, an absorber (Q.sub.out) in fluid communication with the generator, a one-way valve disposed between the generator and the absorber configured to allow passage of the refrigerant and absorbent fluid from generator to the absorber, and a pump (W.sub.in) in fluid communication with the generator and the absorber, configured to increase the pressure of the refrigerant and absorbent solution moving from the absorber to the generator; a microwave heat source coupled to the generator, wherein the microwave heat source provides heat to the generator; an automobile exhaust heat source coupled to a storage unit, wherein the automobile exhaust heat source increases the heat of thermal storage fluid in the system which is stored in a storage unit in fluid communication with the generator; and solar panels coupled to the storage unit, wherein the solar panels heat the thermal storage fluid.

2. The high exergy efficient hybrid solar vapor absorption system of claim 1, wherein the solar panels are also coupled to the generator, wherein the solar panels provide heat to the generator.

3. The high exergy efficient hybrid solar vapor absorption system of claim 1, wherein the thermal storage fluid is circulated through a vehicle radiator, a vehicle exhaust pipe, a solar collector, or a combination thereof, and is then stored in the storage unit in fluid communication with the generator.

4. The high exergy efficient hybrid solar vapor absorption system of claim 1, wherein the microwave heat source is dielectric volumetric heating using microwaves.

5. The high exergy efficient hybrid solar vapor absorption system of claim 1, wherein the refrigerant and the absorbent are differentially heated.

6. The high exergy efficient hybrid solar vapor absorption system of claim 1, wherein the refrigerant consists of the group selected from: R23; R32; R134a; R404A; R407A; R407C; R407F (PERFORMAX LT); and R410A or a combination thereof.

7. The high exergy efficient hybrid solar vapor absorption system of claim 1, wherein the absorbent is bromobenzene.

8. The high exergy efficient hybrid solar vapor absorption system of claim 1, wherein the ratio of refrigerant to absorbent is 40:60.

9. The high exergy efficient hybrid solar vapor absorption system of claim 1, wherein the high exergy efficient hybrid solar vapor absorption system is portable.

10. The high exergy efficient hybrid solar vapor absorption system of claim 1, wherein the high exergy efficient hybrid solar vapor absorption system achieves at least 0.5 tons of refrigeration.

11. The high exergy efficient hybrid solar vapor absorption system of claim 2, wherein the automobile exhaust is provided by an internal combustion engine.

12. The high exergy efficient hybrid solar vapor absorption system of claim 1, wherein the storage tank volume is at least 7 gallons.

13. The high exergy efficient hybrid solar vapor absorption system of claim 1, further comprising throttle valve configured to cause the refrigerant and absorbent solution to flow from the generator to the absorber.

14. The high exergy efficient hybrid solar vapor absorption system of claim 1, wherein the energy storage capacity is 200 J/g on average.

15. The high exergy efficient hybrid solar vapor absorption system of claim 1, wherein the high exergy efficient hybrid solar vapor absorption system uses at least two generators and at least two absorbers all in fluid communication with each other including the condenser and the evaporator.

16. A method of increasing exergy efficiency in a solar absorption system, comprising: an evaporator, the evaporator configured to cause evaporation of at least part of a refrigerant and absorbent solution, and cooling of the refrigerant and absorbent solution; a condenser in fluid communication with the evaporator, the condenser configured to decrease temperature of a gas contained therein thereby transitioning the gas into a liquid state; a thermal compressor in fluid communication with the evaporator and the condenser; wherein the refrigerant and absorbent solution flows throughout the high exergy efficient hybrid solar vapor absorption system including at least the evaporator, the condenser, and the thermal compressor; an expansion valve coupling together the evaporator and the condenser, wherein the expansion valve directs flow of the refrigerant and absorbent solution from the condenser to the evaporator; wherein the thermal compressor increases a pressure of the refrigerant and absorbent solution, thereby causing the refrigerant and absorbent solution to flow from the evaporator to the condenser; wherein the thermal compressor comprises: a generator (Q.sub.in) receiving solar energy, an absorber (Q.sub.out) in fluid communication with the generator, a one-way valve disposed between the generator and the absorber configured to allow passage of the refrigerant and absorbent fluid from generator to the absorber, and a pump (W.sub.in) in fluid communication with the generator and the absorber, configured to increase the pressure of the refrigerant and absorbent solution moving from the absorber to the generator; a microwave heat source coupled to the generator, wherein the microwave heat source provides heat to the generator; an automobile exhaust heat source coupled to a storage unit, wherein the automobile exhaust heat source increases the heat of thermal fluid in the system which is stored in a storage unit in fluid communication with the generator; and solar panels coupled to the storage unit, wherein the solar panels heat the thermal fluid system.

17. The method of claim 16, wherein the thermal fluid is circulated through a vehicle radiator, a vehicle exhaust pipe, a solar collector, or a combination thereof, and is then stored in the storage unit in fluid communication with the generator.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) For a fuller understanding of the instant application, reference should be made to the following detailed description, taken in connection with the accompanying drawings, in which:

(2) FIG. 1 depicts a flow diagram of benefits using microwave assisted hybrid solar vapor absorption refrigeration systems for sustainable cold chain, according to an embodiment of the claimed subject matter.

(3) FIG. 2 is a graphical illustration depicting average solar radiation per day in the State of Florida versus energy generation.

(4) FIG. 3 is a schematic of an embodiment of the claimed subject matter.

(5) FIG. 4A is a schematic of a vapor absorption refrigeration cycle.

(6) FIG. 4B is a schematic of a hybrid vapor absorption refrigeration cycle, according to an embodiment of the claimed subject matter.

(7) FIG. 5 depicts a semi-truck and stats thereof.

(8) FIG. 6 depicts a generator as a component of the system, according to an embodiment of the claimed subject matter.

(9) FIG. 7 depicts an absorbent tank as a component of the system, according to an embodiment of the claimed subject matter.

(10) FIG. 8 depicts an exhaust heat exchanger as a component of the system, according to an embodiment of the claimed subject matter.

(11) FIG. 9 depicts a solar panel apparatus as a component of the system, according to an embodiment of the claimed subject matter.

(12) FIG. 10 depicts heat storage unit as a component of the system, according to an embodiment of the claimed subject matter.

(13) FIG. 11 depicts a microwave radiation heating unit as a component of the system, according to an embodiment of the claimed subject matter.

DETAILED DESCRIPTION

(14) In the following detailed description, reference is made to the accompanying drawings, which form a part thereof, and within which are shown by way of illustration specific embodiments by which the claimed subject matter may be practiced. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present application. These embodiments are described in sufficient detail to enable those of ordinary skill in the art to practice the present disclosure, and it is to be understood that other embodiments may be utilized, and that structural, logical, and electrical changes may be made within the scope of the disclosure.

(15) From the following descriptions, it should be understood that components of the embodiments as generally described and illustrated in the figures herein could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of various embodiments, as represented in the figures, is not intended to limit the scope of the disclosure, but is merely representative of various embodiments. While the various aspects of the embodiments are presented in drawings, the drawings are not necessarily drawn to scale unless specifically indicated.

(16) The following description provides specific details, such as material types, compositions, material thicknesses, and processing conditions in order to provide a thorough description of embodiments of the disclosure. However, a person of ordinary skill in the art will understand that the embodiments of the disclosure may be practiced without employing these specific details. Indeed, the embodiments of the disclosure may be practiced in conjunction with conventional techniques employed in the industry. Only those process acts and structures necessary to understand the embodiments of the disclosure are described in detail below. A person of ordinary skill in the art will understand that some process components are inherently disclosed herein and that adding various conventional process components and acts would be in accord with the disclosure. In this description, specific implementations are shown and described only as examples and should not be construed as the only way to implement the present disclosure unless specified otherwise herein.

(17) Illustrations presented herein are not meant to be actual views of any particular material, component, or system, but are merely idealized representations that are employed to describe embodiments of the disclosure. Referring in general to the following description and accompanying drawings, various embodiments of the present disclosure are illustrated to show its structure and method of operation. Common elements of the illustrated embodiments may be designated with similar reference numerals. It should be understood that the figures presented are not meant to be illustrative of actual views of any particular portion of the actual structure or method, but are merely idealized representations employed to more clearly and fully depict the present disclosure defined by the claims below.

(18) It should be understood that any reference to an element herein using a designation such as first, second, and so forth does not limit the quantity or order of those elements, unless such limitation is explicitly stated. Rather, these designations may be used herein as a convenient method of distinguishing between two or more elements or instances of an element. Thus, a reference to first and second elements does not mean that only two elements may be employed there or that the first element must precede the second element in some manner. Also, unless stated otherwise a set of elements may comprise one or more elements.

(19) Any headings used herein should not be considered to limit the scope of embodiments of the disclosure as defined by the claims below and their legal equivalents. Concepts described in any specific heading are generally applicable in other sections throughout the entire specification.

(20) As used herein, about means approximately or nearly and in the context of a numerical value or range set forth means15% of the numerical. In an embodiment, the term about can include traditional rounding according to significant figures of the numerical value. In addition, the phrase about x to y includes about x to about y.

(21) It should be noted that ratios, concentrations, amounts, and other numerical data may be expressed herein in a range format. It is to be understood that such a range format is used for convenience and brevity, and thus, should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. To illustrate, a concentration range of about 0.1% to about 5% should be interpreted to include not only the explicitly recited concentration of about 0.1 wt % to about 5 wt %, but also include individual concentrations (e.g., 1%, 2%, 3%, and 4%) and the sub-ranges (e.g., 0.5%, 1.1%, 2.2%, 3.3%, and 4.4%) within the indicated range.

(22) As used in this specification and the appended claims, the singular forms a, an, and the include plural referents unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term or is generally employed in its sense including and/or unless the context clearly dictates otherwise.

(23) The phrases connected to and coupled to refer to any form of interaction between two or more entities, including mechanical, electrical, magnetic, electromagnetic, fluid, and thermal interaction. Two components may be connected or coupled to each other even though they are not in direct contact with each other. For example, two components may be coupled to each other through an intermediate component.

(24) Referring in general to the following description and accompanying drawings, various embodiments of the present disclosure are illustrated to show its structure and method of operation. Common elements of the illustrated embodiments may be designated with similar reference numerals. Accordingly, the relevant descriptions of such features apply equally to the features and related components among all the drawings. Any suitable combination of the features, and variations of the same, described with components illustrated in FIG. 1, can be employed with the components of FIG. 2, and vice versa. This pattern of disclosure applies equally to further embodiments depicted in subsequent figures and described hereinafter. It should be understood that the figures presented are not meant to be illustrative of actual views of any particular portion of the actual structure or method, but are merely idealized representations employed to more clearly and fully depict the present disclosure defined by the claims below.

(25) All referenced publications are incorporated herein by reference in their entirety.

(26) Furthermore, where a definition or use of a term in a reference, which is incorporated by reference herein, is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.

(27) A heat pump is a device for delivering heat or cooling to a system, whereas a refrigerator is a device for removing heat from a system. Thus, a refrigerator may be considered a type of a heat pump. Throughout the specification, reference is made to a heat pump with the understanding that the designation of refrigerator, air conditioner, water heater, cogeneration system (also referred to as combined heat and power or CHP system, which is the use of a heat engine or a power station to simultaneously generate both electricity and useful heat), and tri generation system (a cogeneration system that additionally produces cooling) could be substituted without changing the operation of the device. The inherent feature of a heat pump is to transport/move thermal energy from a heat source to a heat sink. The use of the term heat pump, thus is broadly applied as the transport of thermal energy from one enthalpy/entropy state to another. Thus, the utilization of heat pumps is not restricted to the generation of heating or cooling, but also for the intrinsic movement of thermal energy in virtually any thermodynamic cycle including means to convert such thermal energy into power generation (e.g., electrical or mechanical energy).

(28) One type of a heat pump is an absorption heat pump. In absorption heat pumps, an absorbent such as water absorbs the refrigerant, typically ammonia, thus generating heat. When the combined solution, also referred to as binary solutions, is pressurized and heated further, the refrigerant is expelled. When the refrigerant is pre-cooled and expanded to a low pressure, it provides cooling. The low-pressure refrigerant is then combined with the low pressure depleted solution to complete the cycle.

(29) The term absorption is widely accepted in the application of heat pumps for cooling.

(30) Absorption, in chemistry, is a physical or chemical phenomenon or a process in which atoms, molecules, or ions enter some bulk phasegas, liquid or solid material. This is a different process from adsorption, since the molecules are taken up by the volume, not by surface. A more general term is sorption which covers adsorption, absorption, and ion exchange.

(31) The term solar energy is defined as energy derived from the sun, which most often refers to the direct conversion of radiated photons into electrons or phonons through a wide range of means. Solar energy is also indirectly converted into additional energy forms such as the heating of ground water (a.k.a. geothermal water).

(32) The term supercritical is defined as the point at which fluids have been exploited above their critical temperatures and pressures.

(33) The term heat pump is defined as the transport of thermal energy extracted from a heat source to a heat sink by means including vapor compression, absorption, and adsorption.

(34) It is an object of the instant application to provide a hybrid, portable, solar vapor absorption refrigeration system that ensures sustainable, clean, and refrigerated transportation with high exergy efficiency. The claimed subject matter can save $17-$30 per 100 miles of refrigerated transportation depending on prevailing oil prices, reduce greenhouse gas emissions by up to 200 tons of CO.sub.2 equivalence, reduce dependency on fossil fuels for refrigerated transportation, and provide technology that is scalable for cold storage and air-conditioning of buildings.

(35) The claimed subject matter maximize exergy efficiency by using the automobile exhaust heat for refrigeration with supplementary heat from solar collectors and dielectric volumetric heating using microwaves or radiofrequency waves. This results in the refrigerated transport process being environmentally and operationally self-sustainable. This will add to the existing knowledge-base of thermodynamics and heat transfer while enhancing curriculum development in refrigeration and air-conditioning. The current disclosure solves the problems discussed above, specifically issues with energy efficiency, environmental sustainability, and food security, as depicted in FIG. 1. In FIG. 1, 100 is the microwave assisted hybrid solar vapor absorption systems for sustainable cold chain food delivery. Environmental sustainability is depicted as 101, energy efficiency is depicted as 102, both leading to food security 103.

(36) As discussed above, in a conventional vapor compression refrigeration system, a refrigerant, which is a compressible, condensable gas, is compressed in a compressor, passed to a condenser where the gas is condensed to a liquid, and passed through an expansion device to a low-pressure evaporator, where evaporation and cooling take place. The compressor in the Rankine cycle solar vapor compression system is driven either by the turbine or by a back-up electric motor.

(37) The claimed subject matter is a hybrid microwave-assisted solar vapor absorption system that converts anergy into exergy and works sustainably without the intermittence associated with the single absorption vapor absorption systems. The heat required for the generator in a vapor absorption system can be provided by preheating the water or other thermal fluids through solar collectors and by using the vehicle's waste heat in conjunction with solar heat, collecting them into circulating water through the vehicle's radiator, the vehicle's exhaust pipe, and a solar collector. This achieves the required generator temperature. By introducing dielectric heating and by differentially heating only the refrigerant fluid and not the absorbent fluid, the required pressure can be achieved, while allowing the absorbent fluid to stay cooler.

(38) In addition, the claimed subject matter provides for a magnetron to provide microwave heating which increases the pressure of the refrigerant. In some embodiments the microwave can increase the temperature of the refrigerant by a thousand fold which will result in an increased pressure of about six-hundred fold or more. The magnetron will use a transverse mode of electromagnetic radiation which is a particular electromagnetic field pattern of radiation measured in a plane perpendicular to the propagation direction of the beam. In some embodiments the waveguide mode of the transverse electromagnetic modes is TE.sub.10. In some embodiments the microwave heating is directed to the generator in the solar vapor absorption refrigeration system.

(39) FIG. 2 indicates the average solar radiation per day in the State of Florida. On average, a surface area of about 50 m.sup.2 would be needed to capture enough sunlight to run the system on solar heat alone. A large amount of heat can be harvested from the vehicle engine's heat rejection system and its exhaust system.

(40) The claimed subject matter integrates solar heat, automobile waste heat, and microwave heating to achieve a high exergy efficient hybrid solar vapor absorption system. An embodiment of the system is depicted in FIG. 3. The system is depicted as 300 with the solar energy 302 and microwaves 304 providing energy to the system. The system 300 further includes a condenser 306, evaporator 308, and an expansion valve 310 disposed between the condenser 306 and evaporator 308. The system 300 further includes a thermal compressor 312. Within thermal compressor 312 the system further includes a generator 314 in fluid communication with absorber 316. The thermal compressor 312 also includes a pump 318. Both the solar energy 302 and microwaves 304 increase heat in the generator 314. In some embodiments the microwaves 304 can provide heat to the system when there is no sun to provide solar energery 302. In some embodiments, another heat source, such as automobile exhaust (not depicted), can provide heat energy to the generator 314. In some embodiments a diesel engine is kept running to provide continuous heat from exhaust to the generator 314.

(41) FIGS. 4A and 4B are schematics of embodiments of vapor absorption refrigeration cycles. FIG. 4A depicts a vapor absorption refrigeration cycle 400. The cycle includes a generator 402, condenser 404, through a throttle valve 406, evaporator 408, absorber 410, and no-return valve 412. The system has a high pressure side 414, and low pressure side 416. The hybrid vapor absorption refrigeration cycle is depicted 420 in FIG. 4B. The cycle includes automobile waste heat 422, solar panels 424, storage unit 426, evaporator 428, condenser 430, absorbent tank 432, and generator 434.

(42) Specifically, an embodiment of the system includes an evaporator 428 (Q.sub.in) and a condenser 430 (Q.sub.out) in fluid communication with each other, and coupled together via an expansion valve 429 that directs flow from the condenser 428 to the evaporator 430. A thermal compressor also communicates with the evaporator and the condenser and directs flow from the evaporator to the condenser. The thermal compressor includes a generator 402 (Q.sub.in) that receives solar energy, an absorber 410 (Q.sub.out), a heat source that directs heat from the generator to the absorber, and a pump 412 (W.sub.in) that increases the pressure of the refrigerant and abosorbent solution from the absorber to the generator. In the schematic depicted an embodiment of the claimed subject matter in FIG. 4A depicting the system 400. The condenser 404 and generator 402 are on the high pressure side 414, while the evaporator 408 and absorber 410 are on the low pressure side 416. The throttle valve 406 is disposed between the evaporator 408 and condenser 404. A pressure change causes cooling in the system, while compression increases heat in the system.

(43) In some embodiments, the system 420 includes the solar panels 424 and automobile waste heat 422 heat water that is stored in storage unit 426. This heated water is then used to direct heat to the generator 434. The evaporator 428 and absorbent tank 432 are linked in an absorbent fluid recirculation system. The evaporator 428 is linked via an expansion valve 429 to the condenser 430. There is a fail safe pressure valve (not depicted) disposed between the evaporator 428 and the generator 434, to ensure the system is protected from excess pressure build up.

(44) The system also utilizes dielectric volumetric heating using microwaves. Microwave heating is a subcategory of dielectric heating at frequencies above 100 MHz, where an electromagnetic wave can be launched from a small dimension emitter and guided through space to the target. Microwave volumetric heating is used to heat liquids, suspensions, or solid in a continuous flow. Microwave volumetric heating has a greater penetration depth, of up to 42 millimetres (1.7 in), which is an even penetration through the entire volume of the flowing product. This is advantageous in commercial applications where increased shelf-life can be achieved, with increased microbial kill at temperatures 10-15 C. (18-27 F.) lower than when using conventional heating systems.

(45) The refrigerant and the absorbent are differentially heated. Throughout the system the thermal fluids, including the refrigerant and the absorbent fluids, are heated differentially. In some embodiments the refrigerant is heated by different aspects of the claimed system including solar energy or waste heat. In some embodiments while the refrigerant is being heated the absorbent is not heated by the same sources in the claimed system, including solar energy or waste heat.

(46) A combination of 40% ozone-friendly HFC Refrigerant R407c--32.8 and -18.2 and 60% absorbent bromobenzene--2.0-0.2 was identified to be effective for a microwave-assisted vapor absorption cycle. Other suitable materials are contemplated herein as well. Other refrigerants contemplated in a non-limiting list: R23; R32; R134a; R404A; R407A; R407C; R407F (PERFORMAX LT); R410A; and/or combinations thereof.

(47) P.A. HILTON refrigeration testing equipment was used to test the efficiency of refrigeration. Efficiency was found to be about 55%, which is comparable to any vapor compression cycle but without the need for a large compressor.

(48) Example

(49) In a particular implementation, a hybrid refrigeration system for semi-trucks (see FIG. 5) to aid in the sustainability in the cold chain. FIG. 5 depicts a semi-truck body with dimensions of 2.6 m16.5 m2.8 m. The Volume outside is 120 m.sup.3 with an inside volume of 116 m.sup.3. FIG. 5 also lists the density of air at 25 C. to be 1.184 kg/m.sup.3. The specific heat capacity of air to be C.sub.p 1.005 kJ/kg C. The mass of air inside the trailer is m.sub.air 137 kg. To determine cooling load, initial trailer temperature is 25 C., and desired trailer temperature is 5 C. The desired cooling time (t) is 2 hours (7200 seconds). With this information, the following can be seen:
Cooling Load of Empty Trailer (Q.sub.Tr)=m.sub.airC.sub.pT
Q.sub.Tr.sub.1=2,760.62 kJ

(50) $\mathrm{Power}\mathrm{Needed}\left(P_{\mathrm{Tr}}\right)=\frac{Q_{\mathrm{Tr}}}{t}$
P.sub.Tr=383.5 Watts

(51) The following is used in determining heat seepage through trailer walls:

(52) TABLE-US-00001 Material Thermal Thickness Conductivity Thermal Material (L) (k) Resistances (R) Aluminum 10 mm $205\frac{W}{m.Math.K}$ $4.9{10}^{-5}\frac{m^{2}K}{W}$ Polystyrene 305 mm $0.02\frac{W}{m.Math.K}$ $10.16\frac{m^{2}K}{W}$ Stainless- Steel 10 mm $16\frac{W}{m.Math.K}$ $6.3{10}^{-5}\frac{m^{2}K}{W}$
Conductance (U)

(53) $U=\frac{1}{R_{\mathrm{Total}}}=0.098\frac{W}{m^{2}K}$
Heat Seepage in Empty Trailer (q.sub.seep)=UAT
q.sub.seep=370 W
Power Needed (P.sub.seep)
P.sub.seep=370 Watts

(54) For example, to determine cooling load of lettuce, the following analysis is undertaken:
Initial Temperature of Lettuce=6 C.
Desired Temperature of Lettuce=5 C.

(55) $\mathrm{Specific}\mathrm{Heat}\mathrm{Capacity}\mathrm{of}\mathrm{Lettuce}\mathrm{Head}=4.02\frac{\mathrm{kJ}}{\mathrm{kg}.Math.C.}$

(56) In the U.S., 30,000 kg is the maximum legal load for a 53 semi-truck.
Cooling Load of Lettuce Heads (Q.sub.C)=m.sub.loadC.sub.pT
Q.sub.C=120,600 kJ
Power Needed (P.sub.C) for 4 hr cooling time
P.sub.C=8,375 Watts

(57) 0$\mathrm{Respiration}\mathrm{Rate}\left(\mathrm{RR}\right)\mathrm{of}\mathrm{Lettuce}\mathrm{Head}=20\frac{\mathrm{mg}{\mathrm{CO}}_2}{\mathrm{kg}.Math.h}$

(58) $\mathrm{Conversion}\mathrm{Factor}\text{:}1\frac{\mathrm{mg}{\mathrm{CO}}_2}{\mathrm{kg}.Math.h}10.639=1\frac{J}{\mathrm{kg}.Math.h}$
Heat of Respiration (q.sub.RR)=mRR
q.sub.RR=1773 Watts
Power Needed (P.sub.RR)
P.sub.RR=1773 Watts
Max Power Needed to Cool
P.sub.Max=P.sub.C
P.sub.Total=8375 Watts

(59) Component materials are based on ideal thermal properties. Sizes of components are based on cooling load determinations and constraints on truck dimensions. For example, sizing of a generator is based on cooling load, specific heat capacity of absorbent, and desired T of 20 C. In some instances, a volume of 3 gallons is used. Sizing safety factor of 2.5 gallons is used, with headspace of 33% more than calculated volume accounted for. FIG. 6 depicts a cross-sectional view showing the 1 gallon volume headspace for vapor and 2 gallons of refrigerant-absorbent combination.

(60) As another example, the size of absorbent tank is designed so the absorbent tank volume is close to generator volume. The following are its design constraints: volume of 2-3 gallons needed, headspace of 0.5-1 gallon needed, and height of tank fixed at 1 ft (0.328 m). FIG. 7 depicts this design, based on these constraints, with a volume of 2.5 gallons, there is 0.5 gallons of head-space, and 1 gallon of refrigerant mixed with 1 gallon of absorbent.

(61) Using a refrigerant in combination, coupled with capillary tube selection, the system's effectiveness can be increased. In general, the refrigerating effect of R407C is less than that of R22, thus increasing the required mass flow for a given capacity. Capillary tubes selected for R22 applications may be used in the system. One of ordinary skill in the art will recognize other capillary tubes that can be used in the system. Change the system using industry acceptable charging methods with the proper amount of R407C. Generally, the system will use the same amount of refrigerant as R22. See the following analysis:
Refrigerant selection: R-407c
Absorbent selection: Bromobenzene
Absorbent volume: 1 gallon
Cooling load of lettuce: 2447.346 W
Refrigerant volume: 1 gallon

(62) The primary energy source used by the current system is the recovered exhaust heat:

(63) $\mathrm{Calorific}\mathrm{Value}\mathrm{of}\mathrm{Diesel}=44\text{,}800\frac{\mathrm{kJ}}{\mathrm{kg}}$

(64) $\mathrm{Density}\mathrm{of}\mathrm{Diesel}=3.1495\frac{\mathrm{kg}}{\mathrm{gal}}$
Power Collectable from Exhaust Heat
P=391,938 Watts
Assume 50% of Power Recovered (P.sub.exhaust)
P.sub.exhaust=195,969 Watts
FIG. 8 depicts an example of an exhaust heat exchange with required surface area of 0.068 m.sup.2.

(65) A supplemental heat source is solar heat collection and recovery. FIG. 9 depicts an example of a solar heat collection and recovery device, showing the different laminations including: glass, absorber, insulation, back sheet, riser pip, header pipe, and aluminum rails.

(66) TABLE-US-00002 TABLE 1 Dimensions of example solar panel. Length 1.981 [m] 6.5 [ft] Width 1.222 [m] 4 [ft] Height 0.080 [m] 3.15 [in] Gross Area 2.42 [m.sup.2] 26 [ft.sup.2]

(67) Application of the solar panel includes a similar analysis of constraints. The following assumptions are made: 90% efficiency, steady-state conditions, and installations on surfaces other than trailer top has negligible benefits.
Design constraint: available surface area on trailer top
Available area=43 m (450 ft{circumflex over ()}2)
Number of panels=13 Units
Closed loop system
Water is the transfer fluid
Depending on solar heat availability, the solar panel can provide an average of about 9.52 kWh/day.

(68) Solar panel thermal conductance determination:

(69) $\frac{1}{U}=\frac{1}{h_c}+\frac{1}{h_{\mathrm{glass}}}+\frac{x}{k_{\mathrm{abs}\mathrm{plate}}}+\frac{x}{k_{\mathrm{ins}}}+\frac{x}{k_{\mathrm{bk}\mathrm{plate}}}$

(70) $\frac{1}{U}=\frac{1}{10\frac{W}{m^{2}K}}+\frac{1}{300\frac{W}{m^{2}K}}+\frac{0.05m}{0.04\frac{W}{\mathrm{mK}}}+\frac{0.0005m}{401\frac{W}{\mathrm{mK}}}+\frac{0.6m}{205\frac{W}{\mathrm{mK}}}$

(71) $\frac{1}{U}=1.36\frac{m^{2}K}{W}$

(72) $U=0.7373\frac{W}{m^{2}K}$

(73) Solar panel heat seepage determination:
Q=UAt

(74) $Q=0.7373\frac{W}{m^{2}K}*31.47m^2*\left(25-18.4\right)$
Q=153.1439[W]

(75) An example of heated synthetic thermal fluid storage is depicted in FIG. 10, showing a cross-section view. In this example, the volume is 7 gallons, with a body of the tank and rounded ends of the tank as depicted. Design of a heat source storage tank follows a similar analysis:
Design Constraint: diameter fixed at 0.772 ft

(76) $V=V_{\mathrm{cylinder}}+V_{\mathrm{Sphere}}={\left(\frac{d}{2}\right)}^{2}h+\left(\frac{4}{3}\right){\left(\frac{d}{2}\right)}^3=0.9362{\mathrm{ft}}^3\left[7\mathrm{gallons}\right]$
Ideal Synthetic Thermal Fluid Properties
Specific heat capacity range=41.84 kJ/kg.Math. C.62.76 kJ/kg.Math. C.
Thermal diffusivity range=3000 mm.sup.2/s4000 mm.sup.2/s
Density=1200 kg/m.sup.3

(77) Thermal conductivity more than 400 times higher than specific heat capacity

(78) The heat storage tank provides power to the system when the truck is powered off. The following analysis discusses maximum backup time of heat storage supply:
Heat Storage Max Temp: 180 C.
Ambient Temp: 25 C.
Volume of Tank: 0.9362 m.sup.3
Tank Capacity
Q=mc.sub.pt
Q=309,048.3 KJ
Duration before Fail-Safe is needed

(79) 0$\mathrm{Time}=\frac{\mathrm{Tank}\mathrm{Capcity}}{\mathrm{Cooling}\mathrm{Load}}=2.5\mathrm{hrs}$

(80) This fail-safe can be microwave heating (i.e., interaction of microwaves with matter other than metallic conductors will be to rotate molecules and produce heat as result of that molecular motion):

(81) TABLE-US-00003 TABLE 2 Refrigerant R407c Absorbent Bromobenzene 32.8 2.0 18.2 0.2 tan.sub. = .554 tan.sub. = 1 Estimated run time: 1 hour 2 kW Magnetron

(82) Using R407c and Bromobenzene as refrigerant/absorbent combination, heat energy storage capacities can be 200 J/g on average. Further, there can be over 200 unique phase change transition temperatures between 40 C. and 151 C., along with consistent, repeatable performance over thousands of thermal (melt/solidify) cycles. The combination is 100% renewable, produced from agricultural sources (not petroleum), and is readily biodegradable and nontoxic.

(83) In a specific example, half-time refrigeration can be achieved by utilizing two generators and two absorbers. One generator and one absorber can generate 2 ToR_not used first time). The second generator and absorber can be used on demand to increase refrigeration.

(84) The device in the claimed subject matter is depicted in FIG. 11 as attached to a semi-truck trailer and in this way a portable system. The system may be larger and still portable if the vehicle it is coupled to is large enough to efficiently support the system. In some instances, the device can be mounted on top of the trailer and the forward end of the trailer just behind the cab of the truck (not depicted).

(85) The advantages set forth above, and those made apparent from the foregoing description, are efficiently attained. While the disclosure is susceptible to various modifications and implementation in alternative forms, specific embodiments have been shown by way of non-limiting example in the drawings and have been described in detail herein. Since certain changes may be made in the above construction without departing from the scope of the instant application, it is intended that all matters contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

(86) The disclosure is not intended to be limited to the particular forms disclosed.

(87) Rather, the disclosure is to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure as defined by the following appended claims and their legal equivalents.

(88) Without further elaboration, it is believed that one skilled in the art can use the preceding description to utilize the claimed subject matter to its fullest extent. The examples and embodiments disclosed herein are to be construed as merely illustrative and exemplary and not a limitation of the scope of the claimed subject matter in any way. It will be apparent to those having skill in the art, and having the benefit of this disclosure, that changes may be made to the details of the above-described embodiments without departing from the underlying principles of the disclosure herein.

(89) It is also to be understood that the following claims are intended to cover all of the generic and specific features of the disclosure herein described, and all statements of the scope of the disclosure that, as a matter of language, might be said to fall therebetween.