Solar Air Conditioning System Research Articles

Simulation of a solar absorption air conditioning system

This paper presents the simulation of a solar-powered absorption air conditioning system with the absorption pair of lithium bromide and water. An attempt is made to increase the COP of the system by partitioning a single storage tank into two parts. In the morning when sunshine is low, the upper part is activated, and in the afternoon, the whole (upper and lower) tank is connected to the collector. The analysis indicates that it is preferable to utilize a partitioned water tank rather than the normal stratified water tank because the cooling effect can be realized much earlier compared to the normal stratified water storage tank. Also, the overall cooling efficiency (cooling load to total solar energy ratio) was found to be higher for the partitioned storage air conditioning system.

Comparison of the theoretical performance of a solar air conditioning system operating with water/lithium bromide and an aqueous ternary hydroxide

This paper compares the theoretical performance of the modelling of a solar absorption air conditioning system operating with water/lithium bromide and an aqueous ternary hydroxide mixture consisting of sodium, potassium and cesium hydroxides in the proportions 40 : 36 : 24 (NaOH : KOH : CsOH). In this paper, plots of the coefficients of performance of a solar air conditioning system operating with these two mixtures are presented. The results showed that similar coefficients of performance are obtained for both mixtures, however, it was found that the system operating with the hydroxides may operate with a higher range of condenser and absorber temperatures and the heat delivered by these components can be removed by air.

99/03355 A feasibility study of a solar desiccant air-conditioning system—Part II: transient simulation and economics

99/03355 A feasibility study of a solar desiccant air-conditioning system—Part II: transient simulation and economics

99/02770 A feasibility study of a solar desiccant air-conditioning system — part I: psychrometrics and analysis of the conditioned zone

99/02770 A feasibility study of a solar desiccant air-conditioning system — part I: psychrometrics and analysis of the conditioned zone

Solar Air-Conditioning System Performance Optimization by TRNSYS Simulation Modelling

A TRNSYS simulation model was developed and used to simulate the long-term seasonal performance of a 4.7kW solar air-conditioning system located on the campus of The University of Hong Kong. The simulation model was first validated by comparing with the operating data of the HKU system and was then used to perform a parametric study by investigating the effects of collector area, storage volume and cooling load. The results of the parametric study led to sets of optimised system parameters for different cooling loads. The simulation study also indicated that an optimised system can yield a solar fraction of 68% and an overall system efficiency of 9.9% with a constant cooling load under the Hong Kong climatic conditions.

Theoretical modelling of a solar air conditioning system for domestic applications

The present work describes the development of a theoretical microcomputer model suitable for performance predictions and investigation of the operational behaviour of a simple solar cooling system for small residential applications. Derived results allow optimization of design and preliminary economic assessment of the system for operation under local weather conditions. It is concluded that, even at the present costs of fossil fuels, electrical energy and mechanical components, solar air conditioning is an economically marginal application when not combined with solar heating.

Performance of a solar-powered air conditioning system in Hong Kong

To study the feasibility of utilizing solar power for comfort cooling in Hong Kong, a solar-powered absorption air-conditioning system was designed and successfully constructed on the campus of the University of Hong Kong (HKU). The system consisted of a flat-plate collector array with a surface area of 38.2 m 2, a 4.7-kW nominal cooling capacity LiBrH 2O absorption chiller, a 2.75-m 3 hot-water storage tank, a cooling tower, a fan-coil unit, an electrical auxiliary heater, a data-acquisition system and the associated control systems. In the present paper, the design of the HKU solar-powered air-conditioning system is described in detail and its performance over an entire cooling season is also discussed and compared with similar systems in Italy and Singapore. It was found that the HKU solar air-conditioning system had an annual system efficiency of 7.8% and an average solar fraction of 55%.

Design of a solar air-conditioning system for peak electrical load shaving

A design optimization and a cost effectiveness analysis were performed for a solar air-conditioning (A/C) system intended to operate in combination with a conventional A/C system in a peak load shaving mode under Kuwait's environmental conditions. A basic design was prepared, and a computer simulation model was used in optimizing system design, type and size of component equipment, mode of operation and control in terms of energy efficiency and cost effectiveness. The optimum design is comprised of good quality flat plate collectors, a buffer tank and a vapor-absorption refrigeration (VAR) chiller arranged in a single heat collection/delivery circuit. System operation was restricted to periods of solar energy availability with the cooling effect employed in cooling part of the chilled water return of the conventional system. The optimally designed solar system proved to be marginally more expensive than the conventional cooling system, though it held a good potential of becoming cost effective. The design for peak load shaving operation resulted in significant improvements in the energy efficiency and cost effectiveness of the system in relation to an equivalent system for stand alone operation.

Absorption heat pump for a potable water supply in a solar house

Solar houses usually have good potential in arid areas. These areas often suffer from not only a shortage of conventional energy sources, but also of potable water supplies. In this study, a solar air-conditioning system including an absorption heat pump, already in production since the early 1980s, is described for potable water production while performing its air-conditioning duty in a solar house. Compiled weather-conditions of the Hurgada area, on the Red Sea coast of Egypt, were employed for the prediction of the system's productivity, if it were installed in such a locality. An evaluation of the system's feasibility has been conducted.

Psychometric technoeconomic assessment and parametric studies of vapor-compression and solid/liquid desiccant hybrid solar space conditioning systems

This communication presents some studies on hybrid vapor-compression (V-C) and solid/liquid desiccant solar air-conditioning systems. Desiccants are used to bring the humidity within the comfort range by partially converting the latent heat load (LHL) into sensible heat load and then meeting this load with conventional V-C cycle. In both the options of hybrid systems consisting of vapor-compression and solid/liquid desiccant cycles, heat rejected from the condenser of the V-C cycle is used to regenerate the desiccants to improve the coefficient of performance ( COP) of the systems. A thermodynamic assessment and technoeconomic feasibility study of hybrid V-C and solid/liquid desiccant solar air-conditioning systems have been presented. It is found that a hybrid system with desiccant cycle is more promising under high latent heat load and higher ambient humidity conditions and significant energy saving can be achieved over standard V-C cooling systems.

Performance Analysis of an Air Drier for a Liquid Dehumidifier Solar Air Conditioning System

Abstract A model was developed for calculating the operating conditions of a non-adiabatic liquid dehumidifier used in solar air conditioning systems. In the experimental facility used for obtaining the data, air and triethylene glycol circulate countercurrently outside staggered copper tubes which are the filling of an absorption tower. Water flows inside the copper tubes, thus cooling the whole system and increasing the mass transfer potential for drying air. The methodology for calculating the mass transfer coefficient is based on the Merkel integral approach, taking into account the lowering of the water vapor pressure in equilibrium with the water glycol solution.

Design and cost evaluations of solar energy and waste heat utilization systems with latent thermal storage unit using form-stable high-density polyethylene.

Conceptual designs and cost evaluations were made for three solar thermal application systems and a waste heat recovery system with a latent thermal storage unit using form-stable high-density polyethylene. A detailed design of the storage unit shows that it is economically competitive with other thermal energy storage devices such as the steam accumulator. The solar air conditioning system and the waste heat recovery system with this storage unit are feasible. On the other hand, the solar thermal power generation systems with collectors of non-tracking and nonconcentrating type are not cost-effective, mainly due to low conversion efficiency arising from the low operating temperature. System simulations of the two promising systems were carried out.

Performance analysis and loadmatching for tracking cylindrical parabolic collectors for solar cooling in arid zones

Line concentrating collectors are being used for heating and cooling. The decisive advantage of these collectors in comparison with other flat-plate collectors when they are used to power absorption cooling systems is their higher working temperature leading to a higher chiller coefficient of performance (COP) and less collector area and chiller capacity. The line concentrator collector uses a small micro-motor to track the sun in its daily east-west cycle. Due to environmental problems in the site (humidity, dust and excessive heat) the tracking system has failed. Major design modifications are explained to run the system trouble free. Absorption chiller testing showed serious limitations in running the system under fired and at higher condenser temperature as the machine produces less than half the expected output. Running the system should be optimized by increasing the generator temperature and decreasing the cooling water temperature (open-cycle cooling from an underground well was used). The major concern for the solar air-conditioning systems is mainly after applying serious energy conservation measures and thermal insulation to the building. There is certain threshold value for system operation and below that limit the system should not operate or it will be wasting electrical energy not saving it.

Performance simulation of a solar air-conditioning system with liquid desiccant

SYNOPSIS A computer simulation of a solar air-conditioning system of the open-cycle. liquid-desiccant type under different climatic conditions is presented. The system makes use of a sprayed coil dehumidifier and regenerating collectors and operates with triethylene glycol as desiccant. Mathematical models of the regenerating collector and dehumidifier were developed, based on correlations obtained from earlier experiments. The computer simulation subprograms for the various system components, as well as the complete system simulation program, were validated by tests of an experimental system with 52 m2 of collectors. With the aid of the system simulation program, the performance of an optimized system serving a hypothetical building located in five different industrial centres of South Africa, was investigated. The system, sized to deliver 90% of the peak cooling load of the building, required 3.32 m2 of collectors in Johannesburg and 4.45 m2 in Durban per kW of peak cooling capacity. The daily coefficie...

Performance simulation of regenerating type solar collectors

A computer simulation of a regenerating-type solar collector is presented. The collector is used for the regeneration of a liquid desiccant and forms part of an open-cycle solar air-conditioning system. Correlations for heat and mass transfer coefficients and air pressure drop in the collector, derived from earlier experiments, were employed in the computer model. Optimum ranges of design parameters and performance trends are indicated.

CAD of a solar absorption air conditioning system

This paper describes a pilot interactive computer program used by midshipmen in the early phases of design of a solar absorption air conditioning system. The model has been made as simple as possible without losing the fundamental relationships of thermodynamics, fluid dynamics and heat transfer theories. The interactive program provides enough information to allow users to evaluate and design their own solar absorption air conditioning units.

Thermal energy storage

Various types of thermal stares for solar systems are surveyed which include: long-term water stores for solar systems; ground storage using soil as an interseasonal energy store; ground-water aquifers; pebble or rock bed storage; phase change storage; solar ponds; high temperature storage; and cold stores for solar air conditioning system. The use of mathematical models for analysis of the storage systems is considered

Solar heating and air conditioning

Application of air conditioning is widespread in the United States; any new system for heating buildings must be at least compatible with it to be commercially viable. A wide variety of options exists to provide air conditioning along with solar heating for buildings. The effectiveness and efficiency of coupling these air conditioning options with solar heating depends strongly on which solar heating system is being contemplated. This paper discusses the relative merits and the state of development of several solar boosted heat pump systems with regard to their ability to provide air conditioning using conventional vapour compression refrigeration cycles. A brief description is given of the status of solar fired air conditioning. Clues to an approach to cool storage in solar air conditioning systems are given by an assessment of cool storage for reducing peak electrical loads from conventional air conditioning equipment. A system using hydrated salts in a rolling cylinder thermal energy storage device for compact and effective cool storage is described. References are given to provide the interested reader with more detailed information.

Modelling of a solar-operated absorption air conditioner system with refrigerant storage

A detailed dynamic model of a solar air conditioning system is reported. The model, including the solar collector and cooling tower, is described in terms of design parameters. Ambient wet and dry bulb temperatures and solar radiation are the required inputs. System temperatures, energy flows and coefficient of performance can be predicted. Careful attention is given to the evaporator model and the control of refrigerant flow. Typical performance results are discussed. Finally several recommendations for future investigations are made.

A comparison of solar absorption air conditioning systems

A computer simulation of solar powered absorption air conditioning systems is discussed. The results of simulations of various systems composed of conventional flat plate or evacuated tube collectors, wet or dry cooling towers, lithium bromide-water or aqua-ammonia working fluids and hot water, chilled water or refrigerant storage alternatives are obtained over a common operating cycle. Performance of the lithium bromide-water working fluid is shown to be superior to aqua-ammonia. Relative performance gains realized with the evacuated tube collector and relative performance losses associated with the dry cooling tower are presented. Chilled water storage is shown to be advantageous for an evacuated collector, dry cooling tower, lithium bromide-water system.