Solid Adsorption Refrigeration Research Articles

An Effective Flat Plate Solar Heating and Cooling Hybrid System

Based on the achievements of solar solid adsorption refrigeration research, a new hybrid heating and cooling system, related to the solar water heater technique, has been proposed. The conversion and utilization of solar energy for cooling and heating are also analyzed. Experiments on a prototype have shown that both the available (residual) and adsorption heats of the adsorbent bed can be recovered efficiently and simply. The results of some simulations of this new flat plate under real solar radiation are given, as well as comparisons with our previous research work. The successful design and assessment of this new flat plate hybrid system should accelerate the practical application of solid adsorption refrigeration driven by solar energy.

Heat and mass transfer in a flat plate solar solid adsorption refrigeration ice maker

A uniform pressure model is presented to describe the heat and mass transfer in an adsorbent bed for a flat plate solar ice maker. This model accounts for heat and mass transfer in a porous bed in a two-dimensional transient process. An experiment has been conducted to validate this model and the calculated results are in good agreement with experiments. With the help of this model, the transient analysis and performance prediction of an intermittent solar powered solid refrigerator can be presented.

Design and performance simulation of a new solar continuous solid adsorption refrigeration and heating hybrid system

In this paper, the design of a new continuous solid adsorption refrigeration and heating hybrid system driven by solar energy was proposed, and its performance simulation and analysis were made under the normal working conditions. Some performance parameters of the system were obtained, and the effects of water mass in water tank on the system's COP cooling, COP heating etc. were discussed. The simulation indicated: the system could refrigerate continuously with such a design, and at the conditions of that the daily sun-radiation is 21.6 MJ, the mean ambient temperature is 29.9°C, the evaporating temperature is 5°C, the heat-collecting coefficient of upper bed η is 60%, and the heat-transfer coefficient between lower bed and ambient α is 2 W/m 2 K, by day a hybrid system of single combined bed could furnish 30 kg hot water of 47.8°C, and had a mean COP cooling of 0.18, a mean COP heating of 0.34, a continuous mean SCP a of 17.6 W/kg, a continuous mean SCP c of 87.8 W/m 2, and a continuous mean SHP c of 165.9 W/m 2; and at night it had a cooling capacity of 0.26 MJ/kg of adsorbent, and a cooling capacity of 1.3 MJ/m 2 of heat-collecting area.

Numerical simulation of heat transfer in regenerator of solid adsorption refrigeration system

In this paper a theoretical model of the heat-transfer processes in a solid adsorbent packed bed is established. Based on discretized energy control equations of the fluid in the heat-transfer coil and transient heat conduction equations of the adsorbent in the bed with unsteady boundary conditions, a numerical analysis is made. Through numerical computation, a coupling temperature distribution in the adsorbent and the heat-transfer coil is obtained. This will make for an optimal design of the solid adsorbent packed bed.

A study of the effects of collector and environment parameters on the performance of a solar powered solid adsorption refrigerator

Based on the heat and mass transfer model validated by experiment, the performance of the plate solar ice-maker is analyzed systemically with the opinion of two-type characteristic parameters, which includes parametric effects of adsorbent bed of solar ice-maker and outer parameters referring to circumstance. A large number of simulations were undertaken to test the performance of the refrigerator for various collector design parameters and environmental parameters. These works are beneficial to further study the optimization design of a solar cooling system.

Experimental study on dynamic performance analysis of a flat-plate solar solid-adsorption refrigeration for ice maker

A flat-plate solid-adsorption refrigeration ice maker has been built for demonstration purposes. The working pair consists of methanol used as the refrigerant and activated carbon as the adsorption medium. The adsorbent bed is constructed of two flat-plate collectors, with a total surface area of 1.5 m 2. Solar radiation can be simulated with quartz lamps and some important parameters such as temperature and pressure of each subsystem can be handled by a computer. The experimental results show that this machine can produce 4–5 kg of ice after receiving 14–16 MJ of radiation energy with a surface area of 0.75 m 2, while producing 7–10 kg of ice after receiving 28–30 MJ of radiation energy with 1.5 m 2. These are the most advanced results for a solar ice maker so far. All these successful achievements will speed up the commercial processing of a solar ice maker.

Study of a solar powered solid adsorption–desiccant cooling system used for grain storage

A hybrid solar cooling system, which combines the technologies of rotary desiccant dehumidification and solid adsorption refrigeration, has been proposed for cooling grain. The key components of the system are a rotary desiccant wheel and a solar adsorption collector. The former is used for dehumidification and the later acts as both an adsorption unit and a solar collector. The heating load from sunshine can thus be reduced to a greater extent since the solar adsorption collector is placed on the roof of the grain depot. Compared with the solid adsorption refrigeration system alone, the new hybrid system performs better. Under typical conditions, the coefficient of performance of the system is >0.4 and the outlet temperature is <20°C. It is believed that the system can be used widely in the regions with abundant solar resources due to such advantages as environmental protection, energy saving and low operation costs. Additionally, some parameters, for example, ambient conditions, the effectiveness of the heat exchanger and evaporative cooler, mass air-flow rate, etc., which affect system performance, are also analyzed.

Simulation of a solid adsorption solar refrigerator using activated carbon/methanol adsorbent/refrigerant pair

A transient model of a solar powered solid adsorption refrigerator using activated carbon/methanol adsorbent/adsorbate pair, developed from first principles, is presented. It is based on the thermodynamics of the adsorption process and the heat and mass transfer equations of the collector/generator/adsorber components and simplified idealization of the condenser and evaporator components. The resulting equations were transformed into explicit finite difference forms for easy implementation on a personal computer in basic. The numerical model computes the collector plate, bond, and adsorbent temperatures, quantity of methanol generated and the solar COP. The model is validated by comparing it with actual field performance data taken from Anyanwu's work. [Design, construction and test run of a solid adsorption solar refrigerator using activated carbon/methanol working pair, Ph.D. Thesis, University of Nigeria, 1996]. The peak plate and tube surface temperatures and methanol generation are predicted to within 3%, 2.5% and 4%, respectively. The peak times and time for commencement of generation were accurately predicted. Based on the observed agreement between measured and predicted values, parametric study of the refrigerator system was undertaken in order to optimize the design.

A study of thermal decomposition of methanol in solar powered adsorption refrigeration systems

To study the long-term performance reliability of a solar powered carbon/methanol ice maker, an investigation of thermal decomposition of methanol on the alloy's surface under solid adsorption refrigeration conditions has been carried out at Monash University. The indoor simulation showed that the thermal decomposition of methanol did occur in the normal solar powered adsorption refrigeration system. Dimethyl-ether and methoxymethyl methyl ether, etc. were found in the decomposition products. The rate of the decomposition depends on the presence of various alloys. These decomposition products (unwanted gases) may be one of the main reasons for the diminishing performance of the solar ice maker. The impact of the unwanted gases on the ideal solar powered solid adsorption refrigeration cycle is also discussed in this paper.

Charcoal-methanol adsorption refrigerator powered by a compound parabolic concentrating solar collector

A compound parabolic concentrating solar collector (CPC) of concentration ratio 3.9 and aperture area 2.0 m 2 was used to power an intermittent solid adsorption refrigerator and ice maker using activated charcoal (carbon) as the adsorbing medium and methanol as the working fluid. The copper tube receiver of the CPC was packed with 2.5 kg of imported adsorbent 207E3, which was only utilised when the performance of activated charcoal (ACJ1, produced from local coconut shells) was found to be inferior to the imported adsorbent. Up to 1 kg of ice at an evaporator temperature of −6°C was produced, with the net solar coefficient of performance (COP) being of the order of 0.02. Maximum receiver/adsorbent temperature recorded was 154°C on a day when the insolation was 26.8 MJ/m −2. Temperatures in excess of 150°C are undesirable since they favour the conversion of methanol to dimethyl ether, a noncondensable gas which inhibits both condensation and adsorption. The major advantage of this system is its ability to produce ice even on overcast days (insolation ∼ 10 MJ/M −2).