This paper presents a review of the available technologies to provide cooling from solar energy for both thermal and photovoltaic ways. Several multi-criteria performance indicators figuring in the literature are presented followed by a pros and cons analysis of the different solar thermal cooling processes. A market study is also carried out to evidence the potential of these solar cooling technologies. Finally, an overview of various solar cooling installations in Europe, Egypt and China is presented.

Solar driven cooling systems: An updated review

PROBLEM TO BE SOLVED: To provide an air-conditioning system which surpasses conventional air-conditioning systems in energy efficiency and makes a cooling tower unnecessary. SOLUTION: This air-conditioning system has a heat pump 1 which forms a first cycle comprising a first evaporator 2, first compressor 3, and condenser 4 and a second cycle comprising a second evaporator 8, second compressor 6, and the comdenser 4, a warm-heat medium passageway which extract the heating capacity of the heat pump 1 from the condenser 4 and circulate it, and cold-heat medium passageways which extract the refrigerating capacity of the heat pump 1 from the first evaporator 2 and circulate it. With the warm- heat medium passageways desiccant airconditioning machines 70A-E are connected and with the cold-heat medium passageways air-conditioning machines having heat-exchange relations with air in the space set off for the air conditioning are connected in a setup to regenerate the desiccant of each of the desiccant air-conditioning machines 70A-E by the heating medium in the warm-heat medium passageways. The heat of the exhaust gas of the desiccant air-conditioning machines 70A-E is collected by the second evaporator 8 and used to heat the warmheat medium by the second cycle. COPYRIGHT: (C)1997,JPO

Air-conditioning system

An air conditioning and dehumidifier system (310) comprising: an air conditioner (312) comprising a cooling unit; a first inlet (316) to the cooling unit drawing air from a controlled area (314); a second inlet (338) to the cooling unit drawing fresh air from outside the area (314); an outlet (324) to the area (314); a condenser (328) with an air inlet (330) into which relatively cool outside air is drawn; and a heated air outlet (334) from the condenser (328); a dehumidifying unit (342) utilizing liquid desiccant, comprising a drying unit (344) having a wet air inlet (346) and dry air outlet (348); a regenerator unit (350); a hot air inlet (352); a wet air outlet (354); and a heat pump that transfers heat from relatively cooler liquid desiccant to relatively warmer liquid desiccant; a conduit connecting the heated air outlet (334) of the air conditioner (312) to the hot air inlet (352) of the dehumidifying unit (342); and a conduit (349) connecting the dry air outlet (348) of the dehumidifying unit (342) to the second inlet (338) of the air conditioner (312).

Dehumidifier/air-conditioning system

A roof top cooling unit has an evaporative cooling section that includes at least one evaporative module that pre-cools ventilation air and water; a condenser; a water reservoir and pump that captures and re-circulates water within the evaporative modules; a fan that exhausts air from the building and the evaporative modules and systems that refill and drain the water reservoir The cooling unit also has a refrigerant section that includes a compressor, an expansion device, evaporator and condenser heat exchangers, and connecting refrigerant piping Supply air components include a blower, an air filter, a cooling and/or heating coil to condition air for supply to the building, and optional dampers that, in designs that supply less than 100% outdoor air to the building, control the mixture of return and ventilation air

Hydronic rooftop cooling systems

A compact and energy efficient air conditioning system is operated with a desiccant material having a high differential adsorption capacity even at lower regeneration temperatures than those in the conventional system. The desiccant assisted air conditioning system comprises a process air path (A) for flowing process air to adsorb moisture from the process air by a desiccant member, and a regeneration air path (B) for flowing regeneration air heated by a heat source to desorb moisture from the desiccant member (103). The desiccant member is arranged so that the process air or the regeneration air flows alternatingly through the desiccant member. The desiccant member comprises an organic polymer material, the organic polymer material comprising an amphoteric ion exchange polymer having an anion exchange group, a cation exchange group and bridging ligands, thereby exhibiting a high differential adsorption capacity.

Desiccant assisted air conditioning system

A hybrid air conditioning system which simultaneously dehumidifies and cools air using standard vapor-compression equipment and aqueous solutions of liquid desiccant. By using a circulating liquid desiccant and an adiabatic humidifier, a more efficient refrigerant cycle is utilized. Moreover, conditioned air can be delivered at the same temperature and absolute humidity as conventional vapor-compression systems but without overworking the compressor.

John L. Peterson

Papers

Hybrid vapor-compression/liquid desiccant air conditioner