• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.4
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• pp.303-311
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• 2011

This study presents a new idea of liquid desiccant dehumidifier with extended surface to improve the compactness. Extended surface is inserted between vertical cooling tubes, and the liquid desiccant flows down along the tube walls and the extended surface as well. Though the extended surface contributes to the increase in the mass transfer area, the effect tends to be limited because less conductive non-metallic materials need to be applied due to the high corrosiveness of liquid desiccant. To analyze the effects of the extended surface insertion, mathematical modelling and numerical integration are performed for the heat and mass transfer in the liquid desiccant dehumidifier. The results show that, though the liquid desiccant on the extended surface is heated due to the moisture absorption, the temperature can be maintained by periodic mixing at the contact points between the tube and the extended surface with the liquid desiccant stream from the tube side at a relatively low temperature. This implies the absorption heat from the extended surface side can be removed effectively by mixing, which leads to a substantial improvement of the dehumidification in the liquid desiccant dehumidifier with extended surface. When the interval of the extended surface, $p_e/L$, is less than 0.1, the dehumidification is shown to increase by more than two times compared with that without extended surface.

• Journal of the Korean Solar Energy Society
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• v.24 no.1
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• pp.53-61
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• 2004

Absorption potential of desiccant solution significantly decreases after absorbing moisture from humid air, and a regeneration process requires a great amount of energy to recover absorption potential of desiccant solution. In an effort to develop an efficient solar water heater, this study examines a regeneration process using hot water obtained from solar water heater to recover absorption potential by evaporating moisture in the liquid desiccant. In this paper, a solar absorption dehumidifying system with solar water heater is suggested to save the electricity for operating an air conditioner. LiGl(lithium chloride) solution was adopted as a liquid desiccant in the proposed system, and hot water obtained from the solar water heater was used for regenerating the liquid desiccant. As a result, it was clear that the dilute LiCl solution could be regenerated by hot water, and the regeneration rate depends mostly on temperature level of liquid desiccant. The regeneration rates were about 2.4kg/h with $40^{\circ}C$, 4.0kg/h with $50^{\circ}C$, and 6.2kg/h with $60^{\circ}C$ of hot water respectively.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.7
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• pp.521-528
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• 2007

The desiccant rotor is the most essential component of desiccant cooling system, but its design relies on manufacturer's experience and principles are not yet clear in spite of a lot of theoretical/experimental work published. The mathematical modeling of desiccant rotor needs solution of coupled partial differential equations of heat and mass transfer. In this study, numerical program is developed and validated using a real desiccant rotor. The calculation results are in reasonable agreement with the experimental data and other available numerical results. Optimization of desiccant rotor on the condition of low regeneration temperature are investigated. The optimal rotor speed at which the process outlet humidity becomes minimized, shows same as that of the system optimization. Compared to high regeneration temperature, broad is the range of optimal speed of low regeneration temperature. Systematic analysis on the optimal area ratio of regeneration to dehumidification section has also been conducted.

• Journal of Hydrogen and New Energy
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• v.34 no.6
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• pp.773-784
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• 2023

In this study, a comparative analysis between an electric heat pump cooling system and a hybrid desiccant cooling system is conducted. Desiccant cooling is a thermal driven system with potentially lower electric power consumption than electric heat pump. Hybrid desiccant cooling system simulation includes components such as a desiccant rotor, direct and indirect evaporative coolers, heat exchangers, fans, and a heat pump system. Using dynamic simulations by climate conditions, house cooling temperatures and power consumption for both systems are analyzed for 16 days period in the summer season under climate scenarios for the year 2100 prediction. The results reveal that the hybrid desiccant cooling system exhibits a 5-18% reduction in electric consumption compared to the heat pump system.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.1
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• pp.9-15
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• 2012

An effectiveness model has been developed from the approximate analytical solution of a rotary desiccant wheel. The resulting equations clearly show that the maximum air temperature and humidity differences are two independent driving forces commonly acting in the heat and mass transfer processes. Comparison with the numerical model from the preceeding study revealed that the effectiveness model could make realistic predictions roughly with 10% uncertainty. The model may be useful for the rough design and analysis of desiccant evaporative cooling systems.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.1
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• pp.29-36
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• 2012

An experimental study has been carried out to investigate the dehumidification characteristics for several operating conditions of a compact desiccant rotor. This problem is of particular interest in the design of a desiccant type of dehumidifier. Room temperature, room humidity, regeneration temperature, revolution speed and frontal air velocity of desiccant rotor are varied as operating conditions. The results obtained indicate that dehumidification rate is increased with an increase in the room humidity while dehumidification effectiveness is not changed much. It is also found that the optimal rotor speed and optimal regeneration temperature exist for maximum dehumidification rate and dehumidification effectiveness.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.6
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• pp.566-573
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• 2004

Comparison of the cooling performance is provided between the desiccant cool-ing systems incorporating a direct evaporative cooler and a regenerative evaporative cooler, respectively. Cycle simulation is conducted, and the cooling capacity and COP are evaluated at various temperature and humidity conditions. The COP of the system with a regenerative evaporative cooler and the regeneration temperature of 6$0^{\circ}C$ is evaluated 0.65 at the outdoor air condition of 35$^{\circ}C$ and 40% RH. This value is found about 3.4 times larger than that of the system with a direct evaporative cooler. Furthermore, incorporating a regenerative evaporative cooler eliminates the need for deep dehumidification in a desiccant dehumidifier that is necessary to achieve low air temperature in the system with a direct evaporative cooler. Subsequently, the regenerative evaporative cooler enables the use of low temperature heat source to regenerate the dehumidifier permitting the desiccant cooling system more beneficial compared with other thermal driven air conditioners.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.3
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• pp.387-393
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• 2008

This paper has dealt with the probability of oyster shell desiccant cooling system driven by renewable energy of photo-volatic effect with fundamental experiment. The test materials for desiccant are activated charcoal, silica-gel, hi-dry, and oyster shell. The experiments were mainly performed with focusing on the observation of surface features, adsorption amounts of the adsorbent species, and the effect of temperature. Oyster shell has sufficient probability for using as desiccant in a air-conditioning system. Moreover, the heat releasing device would be attached in the system, the system based with oyster shell can be operated with high efficiency.

• Journal of Institute of Convergence Technology
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• v.2 no.2
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• pp.40-48
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• 2012

A small domestic desiccant dehumidifier is modelled using effectiveness models for a desiccant wheel and a wet-air condenser. The desiccant wheel and condenser models are used to compose a system model in the form of a set of simultaneous linear algebraic equations, which is solved by Gauss method. The system model is used to simulate the behaviour of a dehumidifier with a 1kW electric air heater. It is found that the maximu COP is about 0.5 and dehumidification capacity is 18kg/day when the ratio of dehumidification area is 0.7. The optimum wheel thickness and face velocity are found 100mm and 1.5m/s, respectively.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.639-644
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• 2009

This study presents the new idea of liquid desiccant system with extended surface to reduce the system size. The extended surface is inserted between vertical cooling/heating tubes to increase the mass transfer area, and the liquid desiccant flows through the tube wall and the extended surface. Mathematical models for heat and mass transfer between liquid desiccant and air stream at tube wall and extended surface are provided. Dimensionless design parameters governing heat and mass transfer phenomena around the tube and the extended surface are identifier, and dimensionless operating parameters depicting system operating condition including flow rate ratio between dehumidification/regeneration processes, and mass flow rate ratio between air stream and liquid desiccant are explained. The effects of the parameters on system performance are summarized.