Numerical Simulation of a Desiccant Bed for Solar Air Conditioning Applications

1991 ◽  
Vol 113 (2) ◽  
pp. 80-88 ◽  
Author(s):  
S. Farooq ◽  
D. M. Ruthven
Keyword(s):  
Numerical Simulation ◽  
Cycle Time ◽  
Air Conditioning ◽  
Removal Rate ◽  
Optimal Choice ◽  
Coefficient Of Performance ◽  
Thermal Coefficient ◽  
Moisture Removal ◽  
Cyclic Operation

The cyclic operation of a desiccant bed used for solar air conditioning applications has been simulated numerically. The results suggest that the optimal choice of desiccant is not seriously limited by the shape of the isotherm since the effect of isotherm shape on the moisture removal rate can be adequately compensated by appropriate adjustment of the cycle time. The conditions required to maximize the moisture removal rate for any given degree of nonlinearity also satisfy the requirements for maximizing the thermal coefficient of performance.

Experimental Investigation of a Desiccant Wheel Cycle

2012 ◽  
Author(s):  
Ali Al-Alili ◽  
Yunho Hwang ◽  
Reinhard Radermacher
Keyword(s):  
Air Conditioning ◽  
Removal Rate ◽  
Dew Point ◽  
Coefficient Of Performance ◽  
Cycle Performance ◽  
Air Conditioners ◽  
Considerable Portion ◽  
Temperature Heat ◽  
Air Conditioning Systems ◽  
Desiccant Material

In hot and humid regions, removal of moisture from the air represents a considerable portion of the air conditioning load. Conventionally, air conditioning systems have to lower the air temperature below its dew point to accomplish dehumidification. Desiccant air conditioners offer a solution to meet the humidity and temperature requirements of buildings via decoupling latent and sensible loads. In this work, the performance of a new desiccant material is investigated experimentally. This desiccant material can be regenerated using a low temperature heat source, as low as 45°C. It also has a unique S-shape isotherm. The effects of the process air stream’s temperature and humidity, the regeneration temperature, the ventilation mass flow rate, and the desiccant wheel’s rotational speed on the cycle performance are investigated. ARI-humid conditions are used as a baseline and the moisture mass balance is maintained within 5%. The results are presented in terms of the moisture removal rate and latent coefficient of performance (COPlat). The results show a desiccant wheel’s COPlat higher than unity when it is coupled with an enthalpy wheel.

Liquid Desiccant Air Conditioning Using Single Storage Solution Tank, Evaporative Cooling, and Marquise-Shaped Solar Collector

2021 ◽  
Vol 143 (11) ◽  
Author(s):  
M. Sajesh ◽  
Geleta Fekadu ◽  
Kalpana ◽  
Sudhakar Subudhi
Keyword(s):  
Solar Collector ◽  
Air Conditioning ◽  
Removal Rate ◽  
Packed Bed ◽  
Solution Temperature ◽  
Moisture Removal ◽  
Liquid Desiccant ◽  
Mass Flowrate ◽  
Experimental Values ◽  
Storage Solution

Abstract The present paper deals with the experimental study of the liquid desiccant air conditioning system using the single storage solution tank. The novelty of the system is that the dehumidification and regeneration are carried out in a single compact unit. The regeneration of solution is done using the marquise-shaped solar collector. The liquid desiccant solution used here is calcium chloride and water. The moisture removal rate (MRR), moisture, and enthalpy effectiveness are used as the performance parameters. The effects of mass flowrate of solution, solution temperature, inlet air temperature, and relative humidity (RH) on the performance are investigated. The experimental outcome shows that when the solution flowrate is increased from 0.263 to 0.437 kg/s, the MRR is improved from 5.08 to 7.82 g/kg and when the RH is increased from 70% to 92%, the MRR is enhanced from 5.56 to 12.45 g/kg. The new correlation for moisture effectiveness is developed based on the experimental values and depending parameters, and also another correlation is developed based on Chung’s correlation (Chung, T.-W., 1994, “Predictions of Moisture Removal Efficiencies for Packed-Bed Dehumidification Systems,” Gas Sep. Purif., 8(4), pp. 265–268).

scholarly journals System Design of Solar Absorption Cooling : A Case Study in Building of Engineering Physics Department UGM

KnE Energy ◽  
2015 ◽  
Vol 2 (2) ◽  
pp. 22
Author(s):  
Andang Widiharto ◽  
Didit Setyo Pamuji ◽  
Atik Nurul Laila ◽  
Fiki Rahmatika Salis ◽  
Luthfi Zharif ◽  
...  
Keyword(s):  
Global Warming ◽  
Solar Collector ◽  
Air Conditioning ◽  
Cooling System ◽  
Renewable Energy Sources ◽  
Coefficient Of Performance ◽  
Thermal Coefficient ◽  
Solar Absorption ◽  
Absorption Cooling ◽  
Solar Absorption Cooling

<p>Air conditioning (AC) is one of the most building’s energy consumer, included in building of Engineering Physisc’s Departement, Universitas Gadjah Mada (UGM). The declining of fossil fuel reserves and the increasing effects of global warming, forcing the world to switch to renewable energy sources. This paper discusses the design of solar absorption cooling system to replace conventional AC in seven lecture halls of Engineering Physic’s Departement, UGM. There are some steps that have been done to design the solar absorption cooling, i.e. do a study of the potential availability of solar energy, calculate the cooling loads, analyze the thermodynamic process of the system, determine the type of collector to be used and calculate area of solar collector needed. The thermal coefficient of performance (COP) of the system designed was about 0.84 which could use some types of flat plate solar collector with each area corresponding to each efficiency values. </p><p><strong>Keyword</strong> : Air conditioning; global warming; solar absorption cooling; solar collector</p>

Solid desiccant dehumidification-based air-conditioning system for agricultural storage application: Theory and experiments

2019 ◽  
Vol 234 (4) ◽  
pp. 534-547 ◽  
Author(s):  
Muhammad H Mahmood ◽  
Muhammad Sultan ◽  
Takahiko Miyazaki
Keyword(s):  
Air Conditioning ◽  
Evaporative Cooling ◽  
Ambient Air ◽  
Coefficient Of Performance ◽  
Postharvest Quality ◽  
Thermal Coefficient ◽  
Humidity Ratio ◽  
Factors Affecting ◽  
Experimental Apparatus ◽  
Quality Of Products

This study experimentally investigates desiccant dehumidification and indirect evaporative cooling for agricultural products' storage. Thermodynamic advantages of the proposed system are highlighted and compared to vapor compression systems. Significance of proposed system is discussed in relation to agricultural storage application. Factors affecting the postharvest quality of products are discussed, and consequently, the psychrometric zones are established for optimum storage. Hydrophilic polymeric sorbent-based desiccant units are used for the experimental investigation. An open-cycle experimental apparatus is setup by which desiccant dehumidification and regeneration processes are analyzed at various conditions. Thereby, a novel correlation is developed by which desiccant dehumidification process can be simulated precisely. The correlation is successfully validated against the experimental data of various conditions. Desiccant air-conditioning cycle is analyzed for two cases (i.e. case-A: dry-bulb temperature = 31 ℃, humidity-ratio = 6 g/kg-DA; and case-B: dry-bulb temperature = 13 ℃, humidity-ratio = 6 g/kg-DA) to investigate the proposed system's applicability for agricultural storage. The results show that the thermal coefficient of performance is highly influenced by ambient air conditions and decreases with the increase in regeneration temperature. The thermal coefficient of performance for case-A is higher as compared to case-B, and for both cases, it increases with the increase in wet-bulb effectiveness of the evaporative cooling unit.

Performance analysis of a liquid desiccant system with an adjustable reflux ratio of regeneration solution

2016 ◽  
Vol 38 (1) ◽  
pp. 89-103 ◽  
Author(s):  
Xiaofeng Niu ◽  
Yue Zhang ◽  
Xing Li ◽  
Yan Tong ◽  
Guangli Zhang
Keyword(s):  
Air Conditioning ◽  
Coefficient Of Performance ◽  
Reflux Ratio ◽  
Thermal Coefficient ◽  
System Configuration ◽  
Liquid Desiccant ◽  
Average Growth Rate ◽  
Air Conditioning System ◽  
Average Growth ◽  
Water Condensation

In the liquid desiccant system, the amount of the diluted solution sent to the regenerator has a great influence on the system performance. The liquid desiccant system with an adjustable reflux ratio of regeneration solution was proposed in the paper, and the effect of the solution regeneration reflux ratio on the system performance was analysed by simulation. The energy consumption, the electric coefficient of performance and the thermal coefficient of performance under different water condensation rates and varied solution regeneration reflux ratio were obtained. The results show that, the overall performance of the liquid desiccant system can be improved by reducing the solution regeneration reflux ratio; a 1% decrease in the reflux ratio leads to a 0.56–1.02% average growth rate of electric coefficient of performance and a 0.51–0.95% average growth rate of thermal coefficient of performance. Moreover, when the regeneration temperature is high and the water condensation rate of the process air is low, the improvement from decreasing the solution regeneration reflux ratio is more significant. However, the reflux ratio cannot be reduced to an unlimited extent. There is a rational optimum range of the reflux ratio to achieve high thermal coefficient of performance, the optimum range under low dehumidifying load is different from that under high load. Practical application: The performance of a liquid desiccant system can be improved by the proposed system configuration with an adjustable reflux ratio of regeneration solution, such novel system configuration could be applied for the design of air conditioning system, which is beneficial for the energy saving in building. Moreover, the rational optimum ranges of the reflux ratio to achieve high coefficient of performance under different dehumidifying loads are obtained, which could provide guidelines for the design and operation management of the liquid desiccant based building air conditioning system.

Performance analysis and mixing ratio selection of mixed liquid desiccant for a dehumidification system

2019 ◽  
Vol 29 (5) ◽  
pp. 711-720 ◽  
Author(s):  
Xiaoqiang Jiang ◽  
Huaming He ◽  
Xingyou Li ◽  
Huimin Mao
Keyword(s):  
Air Conditioning ◽  
Removal Rate ◽  
High Energy ◽  
Dew Point ◽  
Moisture Removal ◽  
Mixing Ratio ◽  
Liquid Desiccant ◽  
Mixed Salt ◽  
Dew Point Temperature ◽  
Selection Of

Liquid-desiccant dehumidification system in building air-conditioning has high energy efficiency in comparison to traditional dehumidification technology that needs to cool air below the dew point temperature. Since the dehumidification process dominates the performance of a liquid-desiccant system, this study aims to develop a deeper understanding in the dehumidification performance of some liquid desiccants. Then, an experiment test was conducted to determine the CaCl2-LiCl mixed liquid-desiccant system in a dehumidification system. The effects of the pure and mixture liquid desiccant solution on the moisture removal rate, refrigerating capacity and dehumidification performance were compared and analysed. Results show that with the increase in the LiCl concentration, the dehumidification capacity and dehumidification coefficient first increased rapidly and then increased slowly after 30% LiCl concentration. According to the economic analysis of mixed salt solution, the mixed LiCl and CaCl2 solution with a mixing ratio of 3:1 would achieve the best optimal dehumidification efficiency and would incur a low system cost under the working conditions of a dry-bulb temperature at 26°C and a relative humidity of 60% of fresh and return air.

High Performance, Solid Desiccant, Open Cooling Cycles

1989 ◽  
Vol 111 (2) ◽  
pp. 176-183 ◽  
Author(s):  
T. S. Kang ◽  
I. L. Maclaine-cross
Keyword(s):  
Low Temperature ◽  
Parametric Study ◽  
Air Conditioning ◽  
High Performance ◽  
Coefficient Of Performance ◽  
Thermal Coefficient ◽  
Temperature Heat ◽  
Advanced Cycles

Solid desiccant, open cooling cycles use low temperature heat efficiently making them attractive for solar air conditioning. Advanced cycles using nearly reversible evaporative coolers have previously been proposed and shown to have high ideal performance. This parametric study shows that, with real components comparable to those used in studies of classical cycles, these open cycles can give more than twice the thermal coefficient of performance of a ventilation cycle.

scholarly journals Performance evaluation of hydrophilic organic polymer sorbents for desiccant air-conditioning applications

2017 ◽  
Vol 36 (1-2) ◽  
pp. 311-326 ◽  
Author(s):  
Muhammad Sultan ◽  
Takahiko Miyazaki ◽  
Shigeru Koyama ◽  
Zahid M Khan
Keyword(s):  
Numerical Simulation ◽  
Performance Evaluation ◽  
Cycle Time ◽  
Air Conditioning ◽  
Isosteric Heat ◽  
Organic Polymer ◽  
Air Conditioning System ◽  
Ps Ii ◽  
Ps I ◽  
Polymer Sorbents

The present study provides performance evaluation of two kinds of crosslinked hydrophilic organic polymer sorbents (PS-I and PS-II) for desiccant air-conditioning applications. In this regard, optimum temperature and humidity zones are established for various air-conditioning applications which include (i) humans’ thermal comfort, (ii) animals’ thermal comfort, and (iii) postharvest storage of fruits/vegetables. Honeycomb-like desiccant blocks composed of PS-I/PS-II are assumed for numerical simulation analysis. The numerical simulation model is programmed into MATLAB which utilizes the scientific relationships of adsorption isotherms, adsorption kinetics, isosteric heat of adsorption, and thermophysical properties for each sorbent. A particular desiccant air-conditioning system design is proposed, and numerical simulation has been conducted for the performance evaluation of PS-I and PS-II. According to the results, PS-I enables higher dehumidification than PS-II at low regeneration temperature (50℃) and cycle time of 60:90 min. It is because the PS-I possesses better water vapor sorption kinetics as compared to PS-II. Although the PS-II enabled higher steady-state adsorption amount but it could not influence the overall system performance. On the other hand, the optimum performance by the PS-II is limited to relatively long cycle time and higher regeneration temperature (≥80℃). It has been concluded that the PS-I is relatively better choice for desiccant air-conditioning, and consequently can be considered for various air-conditioning applications. Furthermore, effects of mass flow rate, isosteric heat of adsorption, regeneration temperature, and cycle time on air humidity ratio and air temperature profiles have been discussed in order to highlight the performance variability of desiccant air-conditioning system.

A Novel Experimental Apparatus of a Liquid Desiccant Air-Conditioning System

2012 ◽  
Vol 516-517 ◽  
pp. 1121-1127
Author(s):  
Qing Zhang ◽  
Jian Hua Liu ◽  
Wen Zhong Gao ◽  
Liang Zhang
Keyword(s):  
Air Conditioning ◽  
Coefficient Of Performance ◽  
Thermal Coefficient ◽  
Liquid Desiccant ◽  
Total Load ◽  
Air Conditioning System ◽  
Refrigeration Equipment ◽  
Experimental Apparatus ◽  
Lithium Chloride Solution ◽  
Definition Of

A novel experimental apparatus of a liquid desiccant air-conditioning system was introduced. The system differed from similar researches in that it could handle the total load of the conditioned space without any refrigeration equipment and it worked in ventilation mode, which could greatly improve the indoor air quality. The schematic diagram of the system was presented and circulating processes of air, water and lithium chloride solution in the system were introduced. The definition of thermal coefficient of performance (TCOP) for the system was introduced and main operating parameters that could affect TCOP were analyzed. The tested TCOP of the system was 0.72～0.98 in summer and 0.30～0.51 in autumn, which showed that liquid discussant air conditioning system was especially suitable for hot and humid conditions.

scholarly journals Thermodynamic Analysis of a Hybrid System Coupled Cooling, Heating and Liquid Dehumidification Powered by Geothermal Energy

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6084
Author(s):  
Aixiang Xu ◽  
Mengjin Xu ◽  
Nan Xie ◽  
Yawen Xiong ◽  
Junze Huang ◽  
...  
Keyword(s):  
Performance Indicators ◽  
Geothermal Energy ◽  
Removal Rate ◽  
Cooling Capacity ◽  
Coefficient Of Performance ◽  
Space Heating ◽  
Moisture Removal ◽  
Air Humidity ◽  
Space Cooling ◽  
Heating Capacity

The utilization of geothermal energy is favorable for the improvement of energy efficiency. A hybrid system consisting of a seasonal heating and cooling cycle, an absorption refrigeration cycle and a liquid dehumidification cycle is proposed to meet dehumidification, space cooling and space heating demands. Geothermal energy is utilized effectively in a cascade approach. Six performance indicators, including humidity efficiency, enthalpy efficiency, moisture removal rate, coefficient of performance, cooling capacity, and heating capacity, are developed to analyze the proposed system. The effect of key design parameters in terms of desiccant concentration, air humidity, air temperature, refrigeration temperature and segment temperature on the performance indicators are investigated. The simulation results indicated that the increase of the desiccant concentration makes the enthalpy efficiency, the coefficient of performance, the moisture removal rate and the cooling capacity increase and makes the humidity efficiency decrease. With the increase of air humidity, the humidity efficiency and moisture removal rate for the segment temperatures from 100 to 130 °C are approximately invariant. The decreasing rates of the humidity efficiency and the moisture removal rate with the segment temperature of 140 °C increases respectively. Six indicators, except the cooling capacity and heating capacity, decrease with an increase of air temperature. The heating capacity decreases by 49.88% with the reinjection temperature increasing from 70 to 80 °C. This work proposed a potential system to utilize geothermal for the dehumidification, space cooling and space heating effectively.

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