Modeling and Simulation of a Desiccant Evaporative Cooling System (original) (raw)
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Performance Analysis of a Desiccant Evaporative Cooling System Under Hot and Humid Conditions
The control of air conditioning latent and sensible load separately by using a desiccant dehumidifier operating in conjunction with evaporative cooler can reduce the air conditioning power requirement significantly. This system can also utilize the alternative resources of energy such as solar, waste heat, and natural gas effectively. In this article a mathematical model of desiccant evaporative cooling has been developed and the performance of the system is analyzed for its feasibility under the climatic conditions of Dhahran, Saudi Arabia. Different performance curves have been drawn to get optimum values of parameters under different operating conditions. Some new parameters such as sensible energy ratio have also been introduced for better prediction of system cooling capacity. The results showed that the proposed system is suitable and feasible solution to meet the high cooling demands for the conditions of Dhahran, Saudi Arabia with performance largely dependent on optimum selection of operating parameters.
An improved desiccant evaporative cooling system, parametric analysis, and system comparison
2020
This paper discusses a new cooling system that improves the performance of the ventilation cycle for the desiccant evaporative cooling system. The present work is compared with previous studies under various conditions of ambient temperature and humidity ratios. All systems are developed and tested by terms of TRNSYS software through which the validation process is also performed. New components are used with different configurations to enhance the cooling of the supplied air. The results of the validation model show a good agreement with the previously studied cycle with average errors of 1.8% and 0.74% for ambient temperature and humidity respectively. The new system recorded higher performance characteristics over the previously studied systems also Exergy efficiency improved by 19.7%.
A review on desiccant based evaporative cooling systems
The air conditioner should control the building sensible and latent load properly in order to provide the indoor comfort conditions. The conventional mechanical vapor compression system usually controls the latent load by the process of condensation of water vapor in which air is cooled below its dew point temperature and then reheated again up to the required supply conditions. The conditions where latent load is dominant these two processes i.e. overcooling and then reheating again will increase the consumption of electrical energy and emission of CO 2 remarkably. To avoid this wastage of primary energy and emission of harmful gases, desiccant based evaporative cooling system is a good alternative to traditional air conditioning system which is cost effective as well as environment friendly. It can be driven by thermal energy which makes a good use of solar energy which is free as well as clean. In this paper, a review of desiccant based evaporative cooling systems has been presented. The present study is undertaken from variety of aspects including background and need of alternative cooling systems, concept of conventional and desiccant based evaporative coolers, system configurations, operational modes, as well as current status of the desiccant based evaporative cooling technology. The review work indicated that the technology of desiccant based evaporative cooler has a great potential of providing human thermal comfort conditions in hot and humid climatic conditions at the expense of less primary resources of energy as compared to conventional cooling systems. Some modified and modern evaporative coolers have also been introduced in this paper.
Comparison of desiccant air conditioning systems with different indirect evaporative air coolers
Energy Conversion and Management, 2016
This paper presents a numerical analysis of three desiccant airconditioning systems equipped with different indirect evaporative air coolers: (1) the cross-flow Maisotsenko cycle heat and mass exchanger (HMX), (2) the regenerative counter-flow Maisotsenko cycle heat and mass exchanger and (3) the standard cross-flow evaporative air cooler. To analyze the desiccant wheel and the indirect evaporative air coolers, the modified e-NTU-model was used. The simulations were performed under assumption that the desiccant wheel is regenerated with air heated to relatively low temperature values (50-60°C), which can be produced with solar panels in typical moderate climatic conditions. It was established that the main advantage of the presented solutions is that they can provide comfort conditions even with less effective dehumidification. The different systems were compared under variable selected operational factors (i.e. inlet air temperature, humidity and regeneration air temperature). The analysis allowed establishing the advantages and disadvantages of presented solutions and allowed estimating their application potential.
Potential of a desiccant-evaporative cooling system performance in a multi-climate country
International Journal of Refrigeration, 2011
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Simulation of a desiccant-evaporative cooling system for residential buildings
One technology that can help reduce the electricity consumption of conventional air-conditioning technology is the coupling of active dehumidification with evaporative cooling. In this case sensible cooling and moisture removal from indoor and outside ventilation air are decoupled. In this study simulation models are developed for a conventional vapor compression based cooling system and a desiccant evaporative cooling system installed in an R-2000 house. Electricity consumption and comfort indices are then predicted for the two systems for three regions of the country with varying sensible heat ratios. It is found that, compared to a conventional system, the desiccant evaporative cooling system can lead to significant electricity consumption reductions and also reduce the number of hours when conditions inside the space are uncomfortable.
Nowadays, the increasing demand of summer cooling is typically covered by electric chillers, often determining electric peak loads and blackouts. Thus, a wide interest is spreading in small scale natural gas-fired cogenerators driving desiccant-based airconditioning systems, which represent interesting alternatives to conventional systems based on vapor compression cooling only. In this article, experimental tests performed on an air handling unit (AHU) equipped with a desiccant wheel (DW), coupled to a small scale cogenerator and an electric chiller are described. A new layout of the desiccantbased AHU is investigated, considering a third flow (the cooling air), besides the process air flow and the regeneration one. A cross-flow heat exchanger between process air and cooling air is used; the cooling air, cooled by an adiabatic humidifier, is aimed to precool the process air exiting the DW. The relevant influence of the heat exchanger and of the humidifier, as well as that of the chiller performance, on global primary energy requirements, water consumption and CO 2 equivalent emissions of the system is experimentally evaluated.
Desiccant-evaporative cooling system for residential buildings
This paper describes a prototype desiccant evaporative cooling system (DEC) and presents its performance in term of indoor humidity control and energy efficiency. Experimental and simulation results show that the desiccant evaporative cooling system can achieve better humidity control and acceptable comfort conditions. The simulation results show that the desiccant cooling system is especially well suited for areas of the country with a high latent load. However the study identified a series of improvement measures to undertake in order to improve the energy efficiency of the unit. Cet article décrit un prototype de système de refroidissement à évaporation par déshydratant (DEC) et décrit sa performance en termes de contrôle de l'humidité intérieure et d'efficacité energétique. Les résultats expérimentaux et ceux de la simulation montrent que le système de refroidissement à évaporation par déshydratant peut permettre un meilleur contrôle de l'humidité et fournir des cond...
International Journal of Refrigeration, 2015
In this paper, three novel desiccant evaporative cooling system configurations are proposed, simulated and compared with the conventional system under a wide range of ambient air temperature (30 : 40°C) and humidity ratio (0.01 : 0.02 kg v /kg a). In configuration-I, a direct/indirect evaporative cooling is inserted before the rotating heat exchanger. However, it is inserted after the rotating heat exchanger for system configuration-II. In configuration-III, an extra direct/indirect evaporative cooling is added in an opposite manner. Validation results confirm that, simulation and experimental results are in a good agreement with average errors of 2.23 and 3.87% for ambient air temperature and humidity ratio, respectively. Energetic analysis revealed that configuration-I has the highest cooling capacity while configuration-III has the highest thermal COP and air handling COP. Exergetic efficiency of config-III is higher than the conventional system with 54% as average value over the range of ambient air humidity.