Abstract:
An auxiliary thermal storage heating and air conditioning system having an output for selectively delivering warm and cool air to the passenger area of a motor vehicle incorporates a reactor containing a metal salt or a complex compound formed by absorbing a polar gas refrigerant on a metal salt comprising a halide, nitrate, nitrite, oxalate, perchlorate, sulfate or sulfite of an alkali metal, alkaline earth metal, transition metal, zinc, cadmium, tin or aluminum, or sodium borofluoride or a double metal halide. In a preferred embodiment, the reactor contains a sorbent/substrate composition comprising a substrate material inert to the polar gas and incorporating the salt or the complex compound. One embodiment utilizes apparatus having a heat exchanger which selectively functions as an evaporator for a cooling mode and a condenser for a heating mode, and inside and outside coils for transferring system generated thermal energy. Another embodiment of the system uses a refrigerant circulatory system having a circuitous refrigerant line and an evaporator and condenser serially disposed within the circuitous line and a multi-channel ventilation system having a blower for forcing air through the channels of the system and to the output, the channels communicating with the evaporator, the condenser, and the reactor.

Description:
BACKGROUND OF THE INVENTION 
     In U.S. Pat. No. 5,901,572 there is disclosed a thermal storage system which provides heating and cooling to the passenger compartment of the vehicle for extended periods of time when the vehicle engine is not operating. The system described comprises a refrigerant circulatory system having a circuitous refrigerant line and an evaporator and condenser serially disposed within the circuitous line operative to vaporize and condense a refrigerant fluid, respectively, a reactor containing a sorbent material for absorbing vaporized refrigerant in fluid communication with the refrigerant line, a heater in thermal communication with the sorbent, and a multi-channel ventilation system having a blower for forcing air through the channels of the system and to the output, said channels communicating with the evaporator, the condenser, and the reactor. The thermal storage system and method of operation disclosed in the aforesaid U.S. Pat. No. 5,901,572 is incorporated herein by reference. 
     SUMMARY OF THE INVENTION 
     The improved auxiliary heating and air conditioning system of the present invention comprises the thermal storage system described in the aforesaid patent utilizing a solid-vapor sorption reactor containing a complex compound formed by adsorbing a polar gas, preferably ammonia, on a metal salt. In a preferred embodiment, the reactor contains a substrate material incorporating the metal salt or the complex compound. Complex compounds incorporating ammonia are capable of absorbing large amounts of the refrigerant, as well as having high reaction rates. By using a sorbent/substrate composition as disclosed hereinafter, the reactor of the system offers improved performance and life expectancy. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a view of a tractor of a tractor-trailer vehicle having a passenger area partitioned into cab and bunk areas; 
     FIG. 2 is a schematic illustration of one embodiment of a one reactor thermal storage-type auxiliary heating and air conditioning system of the present invention; 
     FIG. 3 is a schematic illustration of a portion of the system shown in FIG. 2 for preheating a vehicle engine; and 
     FIG. 4 is a schematic illustration of another embodiment of a one reactor thermal storage-type auxiliary heating and air conditioning system of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 shows a tractor  10  of a tractor-trailer vehicle. The tractor portion  10  of the tractor trailer vehicle includes an interior space that defines a passenger compartment  12  which is further partitioned, as by curtain  13 , into a cab area  14  and a bunk or sleeper area  15 . The bunk or sleeper area can be used by the driver of the vehicle  10  for periodic rest breaks during long runs. During operation of the vehicle, the passenger compartment  12  is generally heated and cooled by a primary heating and air conditioning system that is powered by the engine (not shown) of the tractor  10 . For heating, the hot engine coolant is piped to a heat exchanger in the passenger compartment. For cooling, the engine drives a rotary compressor which compresses and drives refrigerant around a conventional air conditioning circuit which has an evaporator coil in the passenger compartment. During the driver&#39;s rest breaks it is desirable to be able to shut down the engine of the tractor  10  in order to save fuel, reduce engine wear, and limit environmental pollution. Although the drawings illustrate operation of the present system in connection with the passenger compartment of a tractor-trailer vehicle, it may be used to heat and air condition the passenger compartment of any type of motor vehicle, thus, including tractor-trailer vehicles, cars, trucks, campers, motor homes, recreational vehicles, busses, certain boats, and small airplanes or any areas of a motor vehicle where the passengers may be located such as, for example, the passenger compartment of a tractor trailer vehicle, just the sleeper area of the passenger compartment of a tractor trailer vehicle, the living area of a camper, motor home, or recreational vehicle, and the living and sleeping quarters of certain boats. 
     In the following description, the terms absorb and absorption are used interchangeably with adsorb and adsorption to refer to the same sorption reaction between a polar gas and a metal salt to form a coordinative complex compound. The heating and air conditioning systems of the invention incorporate and utilize a solid-vapor sorption reactor containing a complex compound formed by absorbing a polar gas on a metal salt. The complex compounds are those disclosed in U.S. Pat. No. Re. 34,259 incorporated herein by reference. During the absorption reaction the volumetric expansion of the complex compound formed is restricted as described in U.S. Pat. Nos. 5,298,231, 5,328,671 and 5,441,716, the descriptions of which are incorporated herein by reference. The preferred polar gaseous reactants are ammonia, water, lower alkanols (C 1 -C 5 ), alkylamines, and polyamines. Sulfur dioxide, pyridine and phosphine may also be used. Ammonia is most preferred. Preferred metal salts include the nitrates, nitrites, perchlorates, oxalates, sulfates, sulfites and halides, particularly chlorides, bromides and iodides of alkali metals, alkaline earth metals, transition metals, particularly chromium, manganese, iron, cobalt, nickel, copper, tantalum and rhenium, as well as zinc, cadmium, tin and aluminum. Double metal chloride or bromide salts, in which at least one of the metals is an alkali or alkaline earth metal, aluminum, chromium, copper, zinc, tin, manganese, iron, nickel or cobalt are also useful. Another salt of special interest is NaBF 4 . Other useful complex compounds are disclosed in U.S. Pat. Nos. 5,186,020 and 5,263,330, the descriptions of which are incorporated herein by reference. Preferred complex compounds used in the reaction of the invention are the following or comprise adsorption/desorption compositions containing at least one of the following as a component. Although in the following complex compounds, numerical values of moles of ammonia (“X”) per mole of salt are given, in some complexes, the mole range given comprises several coordination steps. For example, in the case of NaBF 4  compounds, a number of different reaction steps occur between the numerical limits given. Typically however, practical considerations only allow for use of a portion of the designed coordination range. Accordingly, the following ranges are intended to be approximate as will be understood by those skilled in the art. 
     
       
         
               
               
               
             
           
               
                   
                   
               
               
                   
                 Complex Compound 
                 X Value 
               
               
                   
                   
               
             
             
               
                   
                 SrCl 2 .X (NH 3 ) 
                 0-1, 1-8 
               
               
                   
                 CaCl 2 .X (NH 3 ) 
                 0-1, 1-2, 2-4, 4-8 
               
               
                   
                 ZnCl 2 .X (NH 3 ) 
                 0-1, 1-2, 2-4, 4-6 
               
               
                   
                 ZnBr 2 .X (NH 3 ) 
                 0-1, 1-2, 2-4, 4-6 
               
               
                   
                 ZnI 2 .X (NH 3 ) 
                 0-1, 1-2, 2-4, 4-6 
               
               
                   
                 CaBr 2 .X (NH 3 ) 
                 0-1, 1-2, 2-6 
               
               
                   
                 CoCl 2 .X (NH 3 ) 
                 0-1, 1-2, 2-6 
               
               
                   
                 CoBr 2 .X (NH 3 ) 
                 0-1, 1-2, 2-6 
               
               
                   
                 CoI 2 .X (NH 3 ) 
                 0-2, 2-6 
               
               
                   
                 BaCl 2 .X (NH 3 ) 
                 0-8 
               
               
                   
                 MgCl 2 .X (NH 3 ) 
                 0-1, 1-2, 2-6 
               
               
                   
                 MgBr 2 .X (NH 3 ) 
                 0-1, 1-2, 2-6 
               
               
                   
                 MgI 2 .X (NH 3 ) 
                 0-2, 2-6 
               
               
                   
                 FeCl 2 .X (NH 3 ) 
                 0-1, 1-2, 2-6 
               
               
                   
                 FeBr 2 .X (NH 3 ) 
                 0-1, 1-2, 2-6 
               
               
                   
                 FeI 2 .X (NH 3 ) 
                 0-2, 2-6 
               
               
                   
                 NiCl 2 .X (NH 3 ) 
                 0-1, 1-2, 2-6 
               
               
                   
                 NiBr 2 .X (NH 3 ) 
                 0-1, 1-2, 2-6 
               
               
                   
                 NiI 2 .X (NH 3 ) 
                 0-2, 2-6 
               
               
                   
                 SrI 2 .X (NH 3 ) 
                 0-1, 1-2, 2-6, 6-8 
               
               
                   
                 SrBr 2 .X (NH 3 ) 
                 0-1, 1-2, 2-8 
               
               
                   
                 SnCl 2 .X (NH 3 ) 
                 0-2.5, 2.5-4, 4-9 
               
               
                   
                 SnBr 2 .X (NH 3 ) 
                 0-1, 1-2, 2-3, 3-5, 
               
               
                   
                   
                 5-9 
               
               
                   
                 BaBr 2 .X (NH 3 ) 
                 0-1, 1-2, 2-4, 4-8 
               
               
                   
                 MnCl 2 .X (NH 3 ) 
                 0-1, 1-2, 2-6 
               
               
                   
                 MnBr 2 .X (NH 3 ) 
                 0-1, 1-2, 2-6 
               
               
                   
                 MnI 2 .X (NH 3 ) 
                 0-2, 2-6 
               
               
                   
                 CaI 2 .X (NH 3 ) 
                 0-1, 1-2, 2-6, 6-8 
               
               
                   
                 CrCl 2 .X (NH 3 ) 
                 0-3, 3-6 
               
               
                   
                 LiCl.X (NH 3 ) 
                 0-1, 1-2, 2-3, 3-4 
               
               
                   
                 LiBr.X (NH 3 ) 
                 0-1, 1-2, 2-3, 3-4 
               
               
                   
                 NaCl.X (NH 3 ) 
                 0-5 
               
               
                   
                 NaBr.X (NH 3 ) 
                 0-5.25 
               
               
                   
                 NaBF 4 .X (NH 3 ) 
                 0.5-2.5 
               
               
                   
                 NaI.X (NH 3 ) 
                 0-4.5 
               
               
                   
                 K 2 FeCl 5 .X (NH 3 ) 
                 0-5, 5-6, 6-11 
               
               
                   
                 K 2 ZnCl 4 .X (NH 3 ) 
                 0-5, 5-12 
               
               
                   
                 Mg(ClO 4 ) 2 .X (NH 3 ) 
                 0-6 
               
               
                   
                 Mg(NO 3 ).X (NH 3 ) 
                 0-2, 2-4, 4-6 
               
               
                   
                 Sr(ClO 4 ) 2 .X (NH 2 ) 
                 0-6, 6-7 
               
               
                   
                 CrBr 3 .X (NH 3 ) 
                 0-3 
               
               
                   
                 CrCl 2 .X (NH 3 ) 
                 0-3, 3-6 
               
               
                   
                 VCl 3 .X (NH 3 ) 
                 0-3, 3-5, 5-6, 6-7, 7-12 
               
               
                   
                 AlCl 3 .X (NH 3 ) 
                 0-1, 1-3, 3-5, 5-6, 6-7, 7-14 
               
               
                   
                 CuSO 4 .X (NH 3 ) 
                 0-1, 1-2, 2-4, 4-5 
               
               
                   
                   
               
             
          
         
       
     
     Especially preferred are any of the CaCl 2 .X (NH 3 ) complexes, SrCl 2 .1-8 (NH 3 ), SrBr 2 .2-8 (NH 3 ), CaBr 2 .2-6 (NH 3 ), CaI 2 .2-6 (NH 3 ), FeCl 2 .2-6 (NH 3 ), FeBr 2 .2-6 (NH 3 ), FeI 2 .2-6 (NH 3 ), CoCl 2 .2-6 (NH 3 ), CoBr 2 .2-6 (NH 3 ), BaCl 2 .0-8 (NH 3 ), MgCl 2 .2-6 (NH 3 ), MgBr 2 .2-6 (NH 3 ), MnCl 2 .2-6 (NH 3 ) and MnBr 2 .2-6 (NH 3 ), and mixtures of two or more thereof. 
     Preferred reactors used in the system incorporate the improvements disclosed in U.S. application Ser. No. 09/304,763 filed May 4, 1999, incorporated herein by reference. More specifically the space between heat exchange surfaces of the reactor are substantially filled with a sorbent/substrate composition comprising a substrate material that incorporates the metal salt or a complex compound produced from the metal salt and a polar gas. The substrate material incorporating the metal salt or complex compound may be a woven material such as a fabric or cloth, an unwoven material such as felt, mat or similar material in which the strands or fibers have been tangled or otherwise mixed, twisted, pressed or packed to form a coherent substrate. Woven fabric layers may be used between unwoven layers of fibers, especially in composites of alternating woven and unwoven fiber layers. Yarn, rope, or strips or ribbons of substrate fabric may also be used for certain rector heat exchanger designs. 
     Specific preferred substrate materials include nylon polymers including non-aromatic nylons or polyamids, aromatic polyamides or aramids, fiberglass, and polyphenylene sulfides. The aramids are preferred for complex compounds operating at reaction temperatures below about 150° C. For higher temperatures, fiberglass and polyphenylene sulfides are preferred, while at temperatures below about 120° C., nylon-based polymer materials are also suitable. Aramids are not recommended at reaction temperatures above about 150° C. Substrate materials having a high thermal conductivity are advantageous since they improve heat transfer properties of the heat exchanger sorber core. The thermal conductivity of aforesaid substrate materials may be enhanced by incorporating highly thermal-conductive materials such as fibers, particulates, etc. into the substrate. 
     To obtain high thermodynamic and mass efficiency of the substrate composition, it is desirable to use a physical form of the material which can be loaded with a high mass fraction of the sorbent. It is preferable that at least 50%, and preferably 70%, and most preferably 85% or more, of the volume of the sorbent/substrate composition comprises the sorbent itself. Thus, a preferred substrate material used to produce the sorbent/substrate composition of the invention has a porosity of about 50% or more and up to about 98. Examples of types of fabric used to meet such open volume and porosity requirements include textile materials such as cloth, fabric, felt, mat, etc., commonly formed by weaving or knitting, as well as non-woven but cohesive forms such as batt or batting and the like. It has been found advantageous to use a substrate material sufficiently gas permeable for the refrigerant gas to pass through and sufficiently low in pore size to prevent small salt particles to penetrate. Although woven materials usually provide superior physical and structural uniformity, the use of non-woven or amorphous fiber substrates may provide for more uniform distribution of solid sorbent throughout the pores, spaces and interstices of the material. 
     The sorbent is incorporated in the substrate material by embedding or impregnating or otherwise combining the two components to form the sorbent/substrate composition to be installed in a sorber heat exchanger according to the invention. The preferred method of incorporating the sorbent into the substrate material is by impregnation. Such impregnation is carried out by any suitable means such as spraying the substrate material with a liquid solution, slurry, suspension or mixture containing the sorbent or soaking the substrate in a liquid solution, slurry or suspension of the sorbent followed by removal of the solvent or carrier by drying or heating, and/or by applying a vacuum. Yet, other method for incorporating sorbent into the substrate include embedding or otherwise distributing fine sorbent particles within the substrate using blowing, blasting or sintering methods and techniques. Moreover, the particles may be directed into or combined with the substrate material at the time the substrate felt or fabric is manufactured, or subsequently. The sorbent may also be melted, for example, as a hydrate, and the liquid sorbent applied to the substrate after or during substrate manufacture. It may be preferred to impregnate the substrate with the absorbent prior to installation in the reactor. However, the substrate may also be installed prior to being impregnated with the solution containing the absorbent salt. 
     The mass diffusion path of the reactors is the distance a gas molecule must travel between the gas distribution surface and the absorbent particle. The specific description and definition of the mass diffusion path length is disclosed in U.S. Pat. No. 5,441,716 and is incorporated herein by reference. In reactors using ammonia as the refrigerant and ammoniated complex compounds, the mean maximum mass diffusion path is preferably below about 15 mm, which corresponds to the preferred mean mass diffusion path length described in the aforesaid incorporated patent. Optimum dimensions are a function of the specific sorbents and refrigerants used in the process, and the operating pressures, approach pressures and temperatures as well as the sorbent loading density and of the substrate material gas permeability. Preferred mean mass diffusion path lengths are below about 15 mm and most preferred are below about 12 mm. The thermal diffusion or thermal path length is dependent on the distance between adjacent heat exchange surfaces, more specifically, the distance from the nearest highly thermally conductive surface to the center of the absorbent mass. For example, for a reactor of the type illustrated in FIG. 7, the thermal path length is one-half of the distance between adjacent fins. Preferably, the thermal path length is less than 4.5 mm, more preferably less than 4 mm and most preferably about 3.0 mm or less. Thus, for finned tube heat exchanger designs, such a thermal path length is equivalent to a reactor fin count of at least four fins per inch of the length (height) of the reactor module. Preferred reactor fin counts are between about 9 and 25 fins per inch (1.4 mm to 0.5 mm thermal path length). 
     The heat exchanger sorber core may be further improved by use of highly thermal conductive materials such as metals or carbon fibers. The incorporation of such materials or additives in the substrate materials will allow the use of finned tube heat exchangers having a lower fin count or less fins per inch than otherwise disclosed in the aforementioned patents. Thus, substrate fabric or felt may contain, in its woven structure, thermally conductive metal, carbon or graphite fiber or particles. The use of such thermally conductive materials is particularly suitable and even preferable where the substrate material is of relatively low thermal conductivity. For example, glass fiber, known for its low thermal conductivity, will be substantially improved by incorporating such thermally conductive fibers. 
     In FIG. 2 there is illustrated schematically a single reactor heating and air conditioning system embodiment of the invention. In the system, reactor  120  comprises one or more reaction chambers containing one or a mixture of the aforesaid complex compounds which have been formed according to the previously described method. The construction of the reactor including the interior reaction chambers or cores, the relative positioning or location of the fins for achieving the desired thermal and mass diffusion path lengths, fin thickness and shapes as well as the description of the means for directing the refrigerant gas into, through and from the reaction chambers are disclosed in the aforesaid U.S. Pat. Nos. 5,328,671 and 5,298,231 and application Ser. No. 09/304,763 and are incorporated herein by reference. Although a single reactor is shown, a “reactor” may comprise a bank of two or more reactors. 
     As shown in FIG. 2, a refrigerant circulatory system is provided and includes a refrigerant line  102  disposed in a circuitous path. A refrigerant condenser  104  and evaporator  106  are spaced apart and serially disposed within the circuitous path of the refrigerant line  102 . Refrigerant circulated through the refrigerant line is vaporized by the evaporator  106  and subsequently condensed to liquid form by condenser  104 . Circulation of the refrigerant is controlled by refrigerant control valve  108 . 
     A blower  130  is provided to circulate air for the auxiliary heating and cooling system. A first air passageway  110  is provided and disposed to intersect the condenser  104 . As is known, condensing liquid releases heat energy. Therefore air blown across the coils of the condenser  104  heats the air and thus transfers the heat generated by condenser  104  to the ambient as shown during vehicle operation. A second air passage  112  is disposed to intersect the evaporator  106 . Air blown by the blower  130  across the evaporator  106  generates a cool air stream (i.e., heat transferred from air to evaporator  106 ) downstream of the evaporator  106  during the vehicle resting cycle. A third passage  114  is also provided and is directed for distributing air through the reactor  120 . Therefore, air blown by the blower  130  across the reactor  120  heats the air and thus transfers the heat generated by reactor  120  to the atmosphere or ambient during the air conditioning cycle, and to the passenger bunk or sleeping area  15  during the heating cycle via third passage  114 . An electric heater element  122  electrically connected to the vehicle alternator may be used to heat the sorbent material within the reactor  120  while the vehicle is operating. However, it will be appreciated that alternative means may be provided to heat the sorbent material. For example, a segment of the engine coolant line may be coiled and disposed within the reactor  120  to heat the material. Alternatively, a segment of the engine oil system may be coiled or otherwise disposed within the sorbent container  120 . As the oil heats, along with the engine temperature, it serves to heat the reactor  120 . In yet another alternative, a burner may be used, fired by fuel used by the engine of the motor vehicle, such as diesel fuel, gasoline, natural gas, propane or other fuel source as previously described. 
     As illustrated, the refrigerant line  102  is also passed through the reactor  120 . Refrigerant in the vapor state is adsorbed into the solid sorbent material. During the discharge cycle, while the vehicle engine is shut down, desorption (as described above) occurs. A blower control valve  131 , refrigerant check valves  136  and  133 , and refrigerant control valve  108  are also provided to facilitate the charging and discharge cycles of the illustrated embodiment. 
     During the charging cycle of the illustrated embodiment, blower control valve  131  is positioned in position  1  as shown. The first check valve  136  is opened and the second check valve  133  and refrigerant control valve  108  are closed. Refrigerant previously adsorbed into the sorbent material is desorbed and passes through the condenser  104  and is liquefied. The output of the blower  130  is directed by blower valve  131  through the first air passage  110  to carry heat from the condenser  104  to the ambient. 
     During the discharge cycle, blower control valve  131  is disposed in position  2  whereby the airflow from the blower  130  is directed through both passages  112  and  114 . The refrigerant control valve  108  and the second check valve  133  are opened and the first check valve  136  is closed. During this stage, the liquid refrigerant passes through the evaporator to change from liquid to vapor state and is delivered to the reactor  120  where it is absorbed. The air delivered through channel  112  is cooled as it passes across evaporator  106 . In contrast, the air passing across the reactor is heated. Auxiliary heating and cooling of the passenger bunk or sleeping area  15  is controlled by the air control valve  131 . When the control valve  131  is disposed in position C—C as shown, cool air transferring down passage  112  is routed to the passenger area  15  to provide auxiliary cooling while warm air passing down air passage  114  is expelled to the ambient. Conversely, if control valve  131  is disposed in position H—H then warm air channeled down passage  114  is expelled into the passenger area  15  to provide auxiliary heating while the cool air channeled down passage  112  is expelled to the ambient. The system illustrated in FIG. 2 may be modified to incorporate a second blower for recirculating inside air which has already been cooled. The cooled inside air may be mixed with outside air, or recirculated through the system without using any outside air. 
     The previously described sorption technology may also be utilized to preheat the vehicle engine in cold weather climates. In this regard, reference is made to FIG. 3, showing a portion of the system described in FIG.  2 . More particularly, the reactor  120  may be disposed in connection with a circuitous refrigerant line  102  and air passage  114  as described above. A line  100 , however, from the vehicle&#39;s coolant system is also disposed in connection with the reactor  120 . A flow valve  101  and fluid pump  105  are serially disposed with the coolant line  100  to control the flow of fluid therethrough. As schematically illustrated (and as is known), the coolant line  100  passes through the vehicle engine  108 . A second flow valve  109  is also provided to control the fluid flow to other components such as a radiator and heater (not shown). 
     While the vehicle is running, the sorbent material within the reactor  120  is charged to store thermal energy, as described in connection with FIG.  2 . In cold weather climates, after the engine has been shut down for a period of time, it may desired to preheat the engine before starting the vehicle. In this regard, the thermal energy stored in the reactor  120  may be transferred to heat the engine coolant within the coolant line  100 . The pump  105  may then circulate the coolant through the engine  108 , to preheat the engine before starting. 
     FIG. 4 is a schematic illustration of yet another embodiment utilizing the aforesaid absorption refrigeration technology for use in heating and cooling of a motor vehicle passenger compartment. In the embodiment illustrated, a single reactor  175  contains a complex compound sorbent as previously described. The reactor comprises one or more reaction chambers containing one or a mixture of the aforesaid complex compounds which have been formed according to the previously described method. The construction of the reactor including the interior reaction chambers or cores, the relative positioning and location of the fins for achieving the desired thermal and mass diffusion path lengths, fin thicknesses and shapes as well as the description of the means for directing the refrigerant gases into, through and from the reaction chambers are as previously described in U.S. Pat. Nos. 5,328,671 and 5,298,231 and application Ser. No. 09/304,763. In the specific single reactor embodiment illustrated in FIG. 4, a thermal storage heater/cooler system is operated as the reactor desorbs ammonia, or other polar gaseous refrigerant, to heat exchanger  173  via refrigerant directing conduit or piping  187 . Solenoid valve  178  is selectively operated to allow the refrigerant to pass between the reactor  175  and the heat exchanger  173 . The heat exchanger  173  alternately acts as a condenser and an evaporator for the refrigerant, functioning as a condenser during the charging phase as desorbed refrigerant from the reactor is directed to the heat exchanger, where it is condensed. The refrigerant is held in the condensed liquid phase in the heat exchanger, or in a reservoir, not shown, until a cooling function is required. For cooling a passenger compartment, the refrigerant is evaporated in heat exchanger  173  and the vapor is directed back to the reactor  175  at which time it is absorbed on the relatively cool sorbent. Heat exchanger  173  and reactor  175  both include heat transfer sections through which a heat transfer fluid is calculated. Suitable heat transfer fluids include ethylene glycol-water, propylene glycol-water, or equivalent anti-freeze compositions known in the art. The heat transfer fluid exchanges heat with the sorbent in reactor  175  and the refrigerant in heat exchanger  173 . An outside coil  172  exchanges heat or thermal energy with the ambient or atmosphere, while the inside coil  171  selectively heats or cools the passenger compartment  170 . Each of the inside and outside coils also is provided with a fan or blower, schematically illustrated, which assists in heat exchange of the coils. As previously noted, a “reactor” may comprise a bank of two or more reactors. 
     The apparatus of the system illustrated in FIG. 4 also includes several control valves such as ganged 4-way valves  181  and  182  and recirculation pumps  176  and  177 . The valves and pumps provide the circulation and direction of the heat transfer fluid via the heat transfer fluid piping  174 , which communicates with the reactor  175  and evaporator  173 , and the inside and outside coils  172  and  171 , respectively. 
     In the embodiment shown, sorbent in reactor  173  is heated by an electric resistive heater element  190  powered by the vehicle alternator as described in the embodiment shown in FIG.  2 . Other means for heating the reactor for driving the desorption reaction include heating the complex compound by direct firing of the sorber tubes or using heat from hot gases of combustion from a liquid or gas fueled burner. Alternatively, the sorbent may be heated by hot engine oil or heated coolant from the vehicle cooling system with a heat exchange coil disposed in heat transfer contact with the sorbent in the reactor. The system illustrated may be selectively operated or operated automatically depending on the outside ambient temperature and the selective requirements of heating or cooling the passenger compartment. A microprocessor may be used in cooperation with thermostats which monitor both inside passenger compartment temperatures as well as outside ambient temperature. Thus, such a system can be operated automatically depending on the selected desired temperature within the passenger compartment, and depending on the outside ambient temperature. Heat rejection from heat exchanger  173  when functioning as a condenser is transferred to ambient through the outside coil by circulation of the heat transfer fluid driven by the pumps and reactor  175  is cooled by the heat transfer fluid from the outdoor coil to initiate absorption of the refrigerant on the sorbent. The system may also be used for engine preheating in cold weather conditions using heat rejected from the absorbing reactor  175 . At the time of engine preheating, heat exchanger  173  receives heat otherwise supplied by the outside coil through recirculation of the coolant driven by the other of the two pumps. 
     In order to facilitate the installation, repair, and replacement, any of the heating and air conditioning systems of the present invention can have a modular design. For example, the sorber cooling system shown in FIGS. 2 and 4 may be located in an auxiliary heating and air conditioning module  96  that is mounted on the exterior of the vehicle as shown in FIG.  1 . The module  96  is interconnected with the heat exchanger  20  in the passenger compartment  12  via the primary and secondary heat transfer fluid circulatory systems. As also shown in FIG. 1, the module  96  can be substantially in the form of a rectangular enclosure which can be easily mounted to the frame of the tractor-trailer vehicle  10  just behind the sleeper area  15  of the cab. If the system is designed with the characteristics given in the example described above, the system can be contained in a module that is no larger than 5 cubic feet. In addition to the position shown in FIG. 1, the module  96  could also be located just behind the sleeper area  15  on the opposite side of the frame or it could be mounted to the exterior of the rear wall of the passenger compartment  12 . 
     Since the heating and air conditioning system is located primarily outside of the passenger compartment  12  of the vehicle, the system can be accessed for repairs quite easily without having to enter the vehicle or open the engine compartment. The modular design and the exterior location also make it easier to retrofit existing trucks with the system since space does not have to be made within the passenger or engine compartments. Similarly, the modular design of the system makes the system easy to replace with another system when the system must be repaired. Moreover, as opposed to auxiliary heating and air conditioning systems that have significant components connected to the engine, connected to the primary air conditioning system, or located in the engine compartment, the exterior location of the module  96  avoids the possibility of any interference with the normal operation of the vehicle.