Desiccant Air Conditioning System Research Articles

Optimization and comparative performance analysis of conventional and desiccant air conditioning systems regenerated by two different modes for hot and humid climates: Experimental investigation

A desiccant air conditioning system is considered a capable alternative to a conventional air conditioning system because of its independent control of temperature, humidity and being eco-friendly. Also, to resolve the problem of more energy consumption for the restoration of a desiccant, structures comprising of desiccant can utilize thermal energy or complete waste heat to revive desiccant material. Therefore, this research work executes an experimental, optimization and comparative examination for conventional and desiccant air conditioning systems regenerated by two different modes, i.e. firstly using (Mode-I) complete waste heat from condenser and secondly using (Mode-II) rod (electric heater) heat for regeneration at different process air inlet temperatures, i.e. (28, 29.5, 31, 32.5, 34, 35.5 and 37 °C), at different process air inlet velocities, i.e. (1.5, 2.5, 3.5 and 4.5 m/s) and a fix (2.5 m/s) regeneration air inlet velocity. Thus, optimization of performance parameters, i.e. VCOP, ECOP, dehumidification effectiveness, moisture removal capacity (kg/hr), DCOP, regeneration effectiveness and regeneration rate (kg/hr), is identified for achieving maximum efficiency of conventional and desiccant air conditioning systems under the above operating conditions.

Effects of different air inlet temperatures and regeneration air inlet velocities on the performance of Hybrid Desiccant Air Conditioning System

A hybrid desiccant air conditioning unit is treated as an effective alternative to the conventional air conditioning system due to independent control of humidity, temperature, and eco-friendliness. The decrease in environmental impact and energy saving is more when the desiccant recovered by utilizing “free” thermal energy. This current work has experimented with a performance study of a hybrid desiccant air conditioning unit for typical humid and hot Indian (Aligarh) climatic conditions. Here, the effects of different air inlet temperatures at the process section, i.e. (28, 29.5, 31, 32.5, 34, 35.5 and 37°C) and regeneration section, i.e. (50-58.8°C) and different regeneration air inlet velocities (2.5 and 4.5 m/s) on the performance of hybrid desiccant air conditioning system are analyzed. Thus, optimization of performance parameters i.e. refrigerating effect, heat rejection rate, VCOP, ECOP, compressor work, dehumidification effectiveness, moisture removal capacity, DCOP, regeneration effectiveness and regeneration rate is identified for attaining maximum efficiency of hybrid desiccant air conditioning system under above operating states.

Performance evaluation of hybrid desiccant air conditioning system regenerated by waste heat from air cooled condenser: Experimental Investigation

Heating ventilation and air conditioning units reject a large quantity of heat to the surroundings as waste. Thus proper reclamation of this unused heat could also enhance the COP of such arrangements and their lesser adverse effect on the environment. Therefore hybrid desiccant air conditioning unit using unused heat from condenser for regeneration can be more effective than the conventional air conditioning unit under hot and humid climatic conditions. In this paper, various performance parameters of hybrid desiccant air conditioning unit using unused heat from condenser is determined at different process air inlet temperatures (28, 29.5, 31, 32.5, 34, 35.5 and 37°C) and different process air inlet velocities, i.e. (1.5, 2.5, 3.5 and 4.5 m/s) and at fix (2.5 m/s) air velocity at regeneration inlet. Refrigerating effect, heat rejection rate, VCOP, ECOP, dehumidification effectiveness, moisture removal capacity and DCOP decreases with increment in different air temperatures at process inlet. While compressor work, regeneration effectiveness and regeneration rate increases with increment in different air temperatures at process inlet. On the other hand, refrigerating effect, heat rejection rate, VCOP, ECOP, dehumidification effectiveness, regeneration effectiveness, and regeneration rate decrease with increased air velocities at process inlet. Whereas compressor work, moisture removal capacity and DCOP increases with an increase in air velocities at the process inlet. Thus, optimization of these performance parameters is determined to achieve the maximum efficiency of the hybrid desiccant air conditioning system under the above operating states.

Performance assessment of a desiccant air-conditioning system combined with dew-point indirect evaporative cooler and PV/T

In this study, a new solid desiccant air-conditioning system configuration integrated with direct and dew-point indirect evaporative coolers and water-cooled photovoltaic-thermal solar collectors (PV/T) is proposed and simulated for a building located in Adana, a humid and hot city on Mediterranean coast of Turkey. New multiple linear regression equations are developed for the performance of desiccant wheel and dew-point indirect evaporative cooler, which are the two crucial components of the air-conditioning system and used in hourly simulations. Building set temperature, exhaust air mixing ratio, suitable warm air source for preheating regeneration air and optimum connection strategy of PV/T collectors to each other are examined in detail. Hourly and daily thermal coefficient of performance (COPth), solar fraction, primary energy consumption and specific primary energy consumption are calculated to evaluate the energetic performance of the system. COPth of the system ranges from 0.28 to 0.40 during the day, with a daily COPth of 0.34. 69% of the thermal energy required to regenerate desiccant wheel can be generated by the PV/T water collectors.

Performance and Economic Investigation of Solar Regenerated Liquid Desiccant Room Air Conditioning Systems using Eco-Friendly Desiccants

Traditional air conditioning systems run on the vapor compression cycle, which utilizes electricity generated from fossil fuels, the reserves of which are fast depleting. Moreover, the refrigerants used in such systems have exacerbated ozone layer depletion and climate change. Liquid desiccant air conditioning (LDAC) systems appear as a favorable option in light of these drawbacks. This paper has developed the numerical model of an LDAC system using a dehumidifier that is internally cooled and has a finned coil. The study of this particular model has been limited in the past. The model has been validated against a reference study available in the literature. Moreover, the commonly used desiccant materials tend to be corrosive and detrimental to the air quality. Therefore, the feasibility of an ionic liquid (65% [Emim]OAc) and an organic salt solution (73% HCOOK) as desiccant materials has also been investigated in this paper. With the proposed scheme for room air conditioning, the air temperature and humidity levels within the range of comfort (21∘C, 53% R.H.) could be supplied to the conditioned space. Performance analysis revealed that the eco-friendly desiccants could achieve dehumidifier and regeneration effectiveness similar to that of the traditionally used corrosive salt solution of calcium chloride (CaCl2). Furthermore, the estimated dehumidifier efficiency of about 76% is found to be higher than that available in the previous studies. Economic analysis provides a comparison of total cost between the conventional and the novel desiccant air conditioning systems and also reveals HCOOK to be a more economical choice as desiccant material.

Experimental study on desiccant evaporative combined chilled air/chilled water air conditioning systems

• A desiccant evaporative combined chilled air/chilled water systems was proposed. • The dynamic characteristics was presented by experimental investigation. • The temperature of the chiller air and the chiller water is below 20℃ and 18℃. • Regeneration temperature and air–water ratio have great impacts on performance. • 70 °C regeneration temperature was recommended in high humidity regions. Evaporative cooling technology is limited by the environmental wet-bulb temperature and is not suitable for humid climates. Desiccant wheels adsorb water vapour, thereby converting high-humidity air into low-humidity air, and they can be regenerated by solar energy or waste heat. In this study, a desiccant evaporative combined chilled air/chilled water air-conditioning system is proposed. The proposed system integrates a desiccant wheel air conditioning system and a direct-evaporative cooler, which can be used for temperature and humidity independent control systems in humid climates. An experimental setup was built and used to test the system performance and important system parameter effects under moderate temperature and humidity (32 °C, 60% RH), moderate temperature and high humidity (32 °C, 80% RH), and high temperature and humidity (36 °C, 80% RH). The results indicated that for the system at a regeneration temperature of 70 °C, the chilled air temperature was lower than 20 °C, the chilled air humidity ratio was lower than 13 g/kg, and the chilled water temperature was lower than 18 °C, which meets the temperature and humidity independent control requirements.

Dicationic-Type Quaternary Ammonium Salts as Candidates of Desiccants for an Air-Conditioning System

Liquid desiccant air conditioners contribute to sustainable living by reducing the electricity consumption. They can be driven with continuous ventilation and thus can prevent airborne transmission of infectious diseases like COVID-19. In order to develop efficient desiccant materials for liquid desiccant air conditioners, we have investigated the dehumidification capability of 21 types of ammonium salts, many of them being ionic liquids. The hygroscopicity of dicationic quaternary ammonium bis(dimethyl or diethylphosphate) is found to increase with the carbon chain length of the spacer group -(CH2)n- that bridges the two terminal cationic moieties of the dication, that is, (CH2)2 < (CH2)3 < (CH2)6. This trend remains unchanged when methyl substituents on the cation and the phosphate anion are replaced by ethyl groups. A high dehumidification capability is obtained for N1,N1,N1,N6,N6,N6-hexamethylhexane-1,6-diaminium bis(dimethylphosphate) ([HMC6][DMPO4]2) and 1,6-diethyl-1,1,6,6-tetramethylhexane-1,6-diaminium bis(diethylphosphate) ([DETMC6][DEPO4]2);their capability per gram reaches almost twice that of CaCl2, and their dehumidification rate is superior to popular solid desiccants. A favorable equilibrium water vapor pressure for the liquid desiccant air-conditioning system is attained for an 80% (w/w) aqueous solution of [HMC6][DMPO4]2. In addition, the 80% aqueous solution of [HMC6][DMPO4]2 affords no corrosive effect on steel, aluminum, and stainless steel and a very weak effect on copper. Dicationic quaternary ammonium bis(dimethyl or diethylphosphate)s are stable compounds;their aqueous solutions produce no odor after storing for over 1 year under ambient conditions. Molecular dynamics simulations are performed to gain insights into the solvation structure, energetics, and transport behavior of water in aqueous solutions of [HMC6][DMPO4]2 and related salts. ©

Progressive Development and Challenges Faced by Solar Rotary Desiccant-Based Air-Conditioning Systems: A Review

A rotary desiccant-based air-conditioning system is a heat-driven hybrid system which combines different technologies such as desiccant dehumidification, evaporative cooling, refrigeration, and regeneration. This system has an opportunity to utilize low-grade thermal energy obtained from the sun or other sources. In this paper, the basic principles and recent research developments related to rotary desiccant-based cooling systems are recalled and their applications and importance are summarized. It is shown that with novel system configurations and new desiccant materials, there is great potential for improving the performance and consistency of rotary desiccant systems; at the same time, the use of solar energy for regeneration purposes can minimize the operating cost to a great extent. Some examples are presented to demonstrate how rotary desiccant air conditioning can be a promising solution for replacing traditional vapor-compression air-conditioning systems. Recent advances and ongoing research related to solar-powered hybrid rotary desiccant cooling systems are also summarized. The hybrid systems make use of a vapor-compression system in order to have better operational flexibility. These systems, although they consume electrical energy, use solar energy as the principal source of energy, and hence, significant savings of premium energy can be obtained compared to conventional vapor-compression systems. However, further research and development are required in order to realize the sustainable operation of solar rotary desiccant air-conditioning systems, as solar energy is not steady. Reductions in capital cost and size, along with improvements in efficiency and reliability of the system is still needed for it to become a player in the market of air conditioning.

Membrane fouling in direct contact membrane distillation for liquid desiccant regeneration: Effects of feed temperature and flow velocity

Membrane fouling is a major challenge of membrane distillation when employed as a regenerator in liquid desiccant air-conditioning systems. The present work investigated the impacts of feed temperature and flow velocity on the occurrence of membrane fouling using a bench-scale direct contact membrane distillation (DCMD) system to regenerate a 27.5 wt% of lithium chloride (LiCl) solution. The membranes used at different operating conditions were characterized and compared by scanning electron microscopy and water contact angle measurement. The results showed that increasing feed inlet temperature significantly improved the DCMD regeneration capacity but reduced the membrane hydrophobicity. The DCMD operated at a higher cross flow velocity exhibited a higher propensity of membrane fouling. Membrane fouling tended to accumulate from loose LiCl crystals to a dense scaling layer with an increase in both feed inlet temperature and cross flow velocity. Membrane cleaning with deionized water was an effective mitigation strategy to remove the LiCl deposition from the membrane surface. It can effectively restore the DCMD regeneration performance and increase the hydrophobicity of the fouled membrane by 10.6%. However, using the post-cleaning membrane increased the risk of membrane wetting in the DCMD regeneration process.

Study of mass transfer in liquid desiccant for dehumidifiers packed by using conventional wooden slats

To reduce electricity consumption, heating ventilation from the airconditioning sector focuses on developing alternative solution electrically-driven vapour-compression system. The liquid desiccant air-conditioning system represents energy efficiency. It is more environmentally friendly as an alternative technology for the dehumidification process, especially in cases with high latent loads to maintain air quality under reduced conditions for comfortable. This technology is more efficient than the vapour compression system in hot and humid climates like Indonesia. This study carries out an experimental investigation to find out how much moisture removal with using a liquid desiccant to absorb humidity in the air and to know general types of correlations for heat and mass transfer in the contactor for the air solution. In this experiment, liquid desiccant will be passed through wooden slats to determine the physical and thermophysical properties of the air. The general equation will be verified by the experimental results using a curve that fits this expected. The result is a decrease in the humidity in the air. It is known from the amount of moisture absorbed by the drying liquid, and the highest is 336.49 g / s and the lowest is 19 g / s. So it can be concluded that the drying liquid that is exposed to air and passing through wooden slats effective removes moisture.

Experimental assessment of mass transfer characteristics of polypropylene surfaces for low flow falling film liquid desiccant air- conditioning applications

Corrosion problem of metallic surfaces has resulted in a bottleneck situation deterring widespread acceptability of liquid desiccant air conditioning systems. In the current experimental study, mass transfer analysis of non-corrosive polypropylene plastic surfaces, Plain and Modified solid circular cylinders, are investigated on an adiabatic vertical falling film tower. The performance of the vertical solid PP circular cylinder surfaces is compared with PP plate surface to deduct suitable surface for the development of low flow liquid desiccant air conditioning systems. It is found that under the tested conditions, the mass transfer coefficient of the Plain PP circular cylinder is 1.65 times superior to Plain PP plate. The optimal mass transfer coefficient of ∼20 g/m2s for the Plain PP circular cylinder is obtained at ∼1.5 ratio of the mass flow rate of liquid to air, whereas the mass transfer coefficient of the Modified PP circular cylinder continuously increases for the studied range of the mass flow rate of liquid to air ratio. Furthermore, a new generalized correlation for Sherwood number is proposed to predict the performance of different types of falling film towers (plastic/metallic) under adiabatic/non-adiabatic operating conditions by incorporating dynamic flow characteristics, driving thermal and mass transfer potential and wetness characteristic factor.The mean effective error of the current correlation against nine experimental datasets is 16.6%.

Assessment of pilot direct contact membrane distillation regeneration of lithium chloride solution in liquid desiccant air-conditioning systems using computer simulation.

Membrane distillation (MD) has been increasingly explored for treatment of various hyper saline waters, including lithium chloride (LiCl) solutions used in liquid desiccant air-conditioning (LDAC) systems. In this study, the regeneration of liquid desiccant LiCl solution by a pilot direct contact membrane distillation (DCMD) process is assessed using computer simulation. Unlike previous experimental investigations, the simulation allows to incorporate both temperature and concentration polarisation effects in the analysis of heat and mass transfer through the membrane, thus enabling the systematic assessment of the pilot DCMD regeneration of the LiCl solution. The simulation results demonstrate distinctive profiles of water flux, thermal efficiency, and LiCl concentration along the membrane under cocurrent and counter-current flow modes, and the pilot DCMD process under counter-current flow is superior to that under cocurrent flow regarding the process thermal efficiency and LiCl concentration enrichment. Moreover, for the pilot DCMD regeneration of LiCl solution under the counter-current flow, the feed inlet temperature, LiCl concentration, and especially the membrane leaf length exert profound impacts on the process performance: the process water flux halves from 12 to 6 L/(m2·h) whilst thermal efficiency decreases by 20% from 0.46 to 0.37 when the membrane leaf length increases from 0.5 to 1.5 m.

Dehumidification and thermal regeneration characterization of binary deep eutectic solvents in liquid desiccant air conditioning systems

The energy-saving propensity of liquid desiccant air dehumidification technique compared with its counterparts, mitigating the limitations of conventional desiccant solutions and the need for energy optimization in indoor space cooling, has invigorated the exploration of alternative desiccant solutions. This study investigates different binary deep eutectic solvents as a potential alternative working fluids in liquid desiccant air conditioning systems. Hydrogen bond acceptors (Choline chloride, N, N-Diethylethanolammonium chloride, 1-Butyl-3-methylimidazolium chloride, ZnCl2) and hydrogen bond donor (Ethylene glycol) were synthesized in different ratios to form binary deep eutectic solvents. The physiochemical, thermophysical and rheological properties of the investigated solutions were characterized and evaluated. DES A1 (mixture of choline chloride and ethylene glycol in ratio 1:2) and DES D1 (1-Butyl-3-methylimidazolium chloride and ethylene glycol in ratio 1:1) were found best among investigated binary DES solutions. The dehumidification and thermal regeneration potential of these promising solutions were further investigated in a humidity chamber and a drying oven, respectively. At 65 % relative humidity, 30 °C air temperature, and 3.77 × 10−4 m2 moisture-desiccant contact area, the estimated dehumidification mass flux of DES A1 and DES D1 are 4.61 × 10−2 and 3 × 10−2 g/m2∙s, respectively. Empirical correlations obtained for deep eutectic solvents moisture absorption in this study provide an error limit between ±2.6 % to ±3.5 %. These solutions are found promising as alternative solutions for dehumidification and thermal regeneration.

Optimization of NTUm allocation between dehumidifier and regenerator in liquid-desiccant air-conditioning system

Abstract Heat and mass transfer capacities of dehumidifier and regenerator significantly affect the performance of a heat pump driven liquid desiccant air-conditioning (HPLDAC) system. When the dehumidifier and regenerator have the same air flow rates, an equal allocation of the total usable number of mass transfer units (NTUm) between the dehumidifier and regenerator is an intuitive choice. However, whether the equal allocation can result in the optimal system performance is still a pending question. Thus, the optimization principle of NTUm allocation between dehumidifier and regenerator in the HPLDAC system is theoretically deduced and illustrated in this study. The results reveal the equal allocation is recommended when the nonlinearity of the isoφ line is insignificant, whereas allocating more NTUm to the dehumidifier than regenerator is recommended when the nonlinearity of the isoφ line is significant. When the NTUm values of the dehumidifier and regenerator are large enough, further increases of the NTUm values show limited effect on performance improvements of the dehumidifier and regenerator. Only when the total NTUm is below 10, does the NTUm allocation optimization play an important role in the system performance improvement, and is a pre-estimation necessary for achieving the optimal system performance.

Performance assessment of hybrid desiccant air conditioning systems: A dynamic approach towards achieving optimum 3E solution across the lifespan

This study aims to assess a hybrid desiccant air conditioning system to provide cooling, heating, and water demand for hot and humid regions using multi-response optimization from the energy, economic, and environmental (3E) perspective. A solar heating system was used to provide the thermal energy required to regenerate the desiccant material. A thermal energy storage unit packed with phase change materials was considered to enhance the solar contribution during periods of low solar radiation. Furthermore, exhaust air of the regeneration process was used to harvest the moisture content of the air to produce fresh water. Using response surface methodology (RSM), a series of novel correlations were achieved for predicting resource consumption, provided thermal comfort, economic, and environmental indicators over the system's lifespan. The results of the dynamic evaluation reveal that the proposed optimum system achieves a higher solar fraction while using a smaller solar collector area. Moisture harvesting is also capable of producing 70% higher water than the system's consumption. The findings show a significant improvement in all 3E indicators compared to reference systems. Moreover, overall results indicate that dynamic and 3E approaches should be employed to achieve the foremost design for desiccant air conditioning systems.

Performance investigation of a solar cascade liquid desiccant regeneration system for hot and humid climates

A new solar cascade regeneration system was developed with the goal of producing a reliable and energy-efficient liquid desiccant regeneration process. This process is specifically designed for liquid desiccant air-conditioning systems in severely hot and humid climates. The regeneration characteristic of this new system is researched and compared with the conventional hollow fiber membrane thermal regeneration system. Results show that the increase of desiccant concentration difference between regenerate and dilute solutions in electrodialysis regenerator will decrease the required heating temperature and energy consumption of the new system, which means the new system can conveniently control the required heating temperature to meet the variable environment condition. With the same environment condition, the new system has lower required heating temperature and energy consumption than the conventional hollow fiber membrane thermal regeneration system. Among all simulation conditions, compared with the conventional hollow fiber membrane thermal regeneration system, the largest heating temperature drop of 7 °C and the highest energy-saving of 14% can be achieved when the new system is applied. It can be concluded that the new solar cascade regeneration system can work stably and reliably under the severe hot and humid climate as its low heating temperature requirement and energy-saving potential.

Experimental analysis of hollow fiber membrane dehumidifier system with SiO2/CaCl2 aqueous desiccant solution

The liquid desiccant air conditioning system is amongst the promising technologies for the provision of efficient air conditioning, particularly in hot humid climate conditions. By their benefits, membrane-based dehumidification systems have drawn large attention. Various techniques are used to enhance the performance of different dehumidification system types. The effect of using calcium chloride nanofluid solution with the added silicate nanoparticles as a desiccant solution in a hollow fiber membrane contactor system investigated experimentally. The airflow rate through the fibers is 11.2 m3/h with inlet relative humidity and temperature of 60 % and 35 °C, respectively. The sensitivity analysis was made to reveal the effect of desiccant temperatures, nanoparticle concentrations, and solution flow rates on sensible, latent, and total effectiveness and 2nd law efficiency of the system. The results indicate that using nanofluid instead of a pure desiccant solution, the values of sensible and latent effectiveness improved at the condition of high inlet solution temperature. The effect of employing nanofluid on exergy performance is the highest for the highest concentration of nanoparticles and inlet solution temperature. The maximum change of exergy destruction rate resulted by using nanofluid solution took place at a maximum flow rate of 244 ml/min for 1% nanofluid concentration. Using 1 % nanofluid instead of a pure solution, the rate of exergy destruction increased by 82 % and 160 % for 20 °C and 26 °C solution temperatures, respectively.

Dynamic model and response characteristics of liquid desiccant air-conditioning system driven by heat pump

The liquid desiccant air-conditioning system is considered as an energy-efficient alternative to the vapor compression system. The dynamic response characteristics of the system under variable cooling load play an important role in the air temperature and humidity control performance of the system. However, the dynamic response characteristics have not been fully revealed in previous studies. Thus, a dynamic model for a heat pump driven liquid desiccant air-conditioning (HPLDAC) system is established to investigate the dynamic response characteristics of the system in this study. Subsequently, experiments were conducted to validate the accuracy of the dynamic model. The simulation results show a good agreement with the experimental data. The simulation results reveal that evaporating water from the solution is a time-consuming process, compared to adding water to the solution. It spends a long time for the HPLDAC system to decrease the high relative humidity of supply air to a low value, which limits the air temperature and humidity control performance of the system. The upper band for the water replenishing value opening (Δφup) is a crucial parameter to improve the limitation. When Δφup decreases from 1.0% to 0.25%, the time consumed to reduce the supply air relative humidity to the new lower set value can be saved by 30.6%.

Dynamic Evaluation of Desiccant Dehumidification Evaporative Cooling Options for Greenhouse Air-Conditioning Application in Multan (Pakistan)

This study provides insights into the feasibility of a desiccant dehumidification-based Maisotsenko cycle evaporative cooling (M-DAC) system for greenhouse air-conditioning application. Conventional cooling techniques include direct evaporative cooling, refrigeration systems, and passive/active ventilation. which are commonly used in Pakistan; however, they are either not feasible due to their energy cost, or they cannot efficiently provide an optimum microclimate depending on the regions, the growing seasons, and the crop being cultivated. The M-DAC system was therefore proposed and evaluated as an alternative solution for air conditioning to achieve optimum levels of vapor pressure deficit (VPD) for greenhouse crop production. The objective of this study was to investigate the thermodynamic performance of the proposed system from the viewpoints of the temperature gradient, relative humidity level, VPD, and dehumidification gradient. Results showed that the standalone desiccant air-conditioning (DAC) system created maximum dehumidification gradient (i.e., 16.8 g/kg) and maximum temperature gradient (i.e., 8.4 °C) at 24.3 g/kg and 38.6 °C ambient air conditions, respectively. The DAC coupled with a heat exchanger (DAC+HX) created a temperature gradient nearly equal to ambient air conditions, which is not in the optimal range for greenhouse growing conditions. Analysis of the M-DAC system showed that a maximum air temperature gradient, i.e., 21.9 °C at 39.2 °C ambient air condition, can be achieved, and is considered optimal for most greenhouse crops. Results were validated with two microclimate models (OptDeg and Cft) by taking into account the optimality of VPD at different growth stages of tomato plants. This study suggests that the M-DAC system is a feasible method to be considered as an efficient solution for greenhouse air-conditioning under the climate conditions of Multan (Pakistan).

An Overview of Recent Studies on the Development of Desiccant Air-conditioning Systems

In the past decades, desiccant cooling systems have received much attention. These systems are considered as an alternative way to decrease energy consumption and greenhouse gas emission in humid and hot locations. To address the importance of desiccant air-conditioning systems, the present research aims to provide an overview of recent studies on the development of desiccant air conditioning system. Another objective is to consider the numerical and theoretical analysis of desiccant systems. Moreover, for the first time, a summary of recent researches regarding the use of Computational Fluid Dynamics (CFD) technique for numerical modeling of desiccant cooling systems has been especially reviewed in detail. Finally, in the present review, the principle of regeneration of liquid desiccant using solar energy have also been considered briefly.