scholarly journals Experimental Investigation of Desiccant Dehumidification Cooling System for Climatic Conditions of Multan (Pakistan)

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5530
Author(s):  
Muhammad Aleem ◽  
Ghulam Hussain ◽  
Muhammad Sultan ◽  
Takahiko Miyazaki ◽  
Muhammad H. Mahmood ◽  
...  
Keyword(s):  
Experimental Data ◽  
Silica Gel ◽  
Air Conditioning ◽  
Ambient Air ◽  
Climatic Conditions ◽  
Coefficient Of Performance ◽  
Thermal Coefficient ◽  
Polymeric Sorbent ◽  
Experimental Apparatus ◽  
Desiccant Material

In this study, experimental apparatus of desiccant dehumidification was developed at lab-scale, using silica gel as a desiccant material. Experimental data were obtained at various ambient air conditions, while focusing the climatic conditions of Multan (Pakistan). A steady-state analysis approach for the desiccant dehumidification process was used, and thereby the slope of desiccant dehumidification line on psychrometric chart (ϕ*) was determined. It has been found that ϕ* = 0.22 in case of silica gel which is lower than the hydrophilic polymeric sorbent, i.e., ϕ* = 0.31. The study proposed two kinds of systems, i.e., (i) standalone desiccant air-conditioning (DAC) and (ii) Maisotsenko-cycle-assisted desiccant air-conditioning (M-DAC) systems. In addition, two kinds of desiccant material (i.e., silica gel and hydrophilic polymeric sorbent) were investigated from the thermodynamic point of view for both system types, using the experimental data and associated results. The study aimed to determine the optimum air-conditioning (AC) system type, as well as adsorbent material for building AC application. In this regard, perspectives of dehumidification capacity, cooling capacity, and thermal coefficient of performance (COP) are taken into consideration. According to the results, hydrophilic polymeric sorbent gave a higher performance, as compared to silica gel. In case of both systems, the performance was improved with the addition of Maisotsenko cycle evaporative cooling unit. The maximum thermal COP was achieved by using a polymer-based M-DAC system, i.e., 0.47 at 70 °C regeneration temperature.

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.

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 ПОДХОД К АНАЛИЗУ ЭФФЕКТИВНОСТИ РЕГУЛИРОВАНИЯ ХОЛОДОПРОИЗВОДИТЕЛЬНОСТИ СИСТЕМ КОНДИЦИОНИРОВАНИЯ ПРИТОЧНОГО ВОЗДУХА

2018 ◽  
pp. 29-33
Author(s):  
Евгений Иванович Трушляков ◽  
Николай Иванович Радченко ◽  
Вениамин Сергеевич Ткаченко
Keyword(s):  
Electric Motor ◽  
Air Conditioning ◽  
Frequency Converter ◽  
Piston Compressor ◽  
Ambient Air ◽  
Climatic Conditions ◽  
Coefficient Of Performance ◽  
Air Cooling ◽  
Refrigeration Capacity ◽  
Air Conditioning Systems

It is determined that the operation of ambient air conditioning systems (AACS) has significant fluctuations in the heat load in accordance with current climatic conditions. This makes very problematic the application of refrigeration compressors with frequency converters, which are very effective for controlling the refrigeration capacity in closed air conditioning systems, in which the temperature control range and, accordingly, fluctuations in thermal load are insignificant in comparison with the ambient air cooling. For the purpose of analyzing the efficiency of controlling the refrigeration capacity of the AACS by changing the electric motor speed of the piston compressor in current climatic conditions, the entire range of changing current thermal loads is divided into two parts according to controlling the refrigeration capacity by appling a frequency converter: the part of effective cooling capacity adjustment without energy losses (without reducing the coefficient of performance) from nominal to its threshold value and the part of reduced refrigeration capacity without its controlling by a frequency converter. It is revealed that for the warmest summer month, the proportion of refrigeration capacity spent for cooling ambient air to the temperature of 10 °C with 50 % frequency controlling the refrigeration capacity is about 10 % of the total amount of that could be produced at nominal refrigeration capacity. At higher temperatures of cooled air is even less. This shows the low efficiency of controlling the refrigeration capacity of the AACS by changing the speed of rotation of the piston compressor electric motor and the need to use other methods of controlling the refrigeration capacity. The proposed approach to analyzing the efficiency of controlling the refrigeration capacity of AACS in current climatic conditions allows not only to estimate the efficiency of refrigeration capacity controlling method but also to reveal the reserves for increasing the efficiency of applying the available refrigeration capacity

scholarly journals Alternative Air-Conditioning Options for Developing Countries

2017 ◽  
Vol 2 (1) ◽  
pp. 76 ◽  
Author(s):  
Muhammad Kashif ◽  
Muhammad Sultan ◽  
Zahid Mahmood Khan
Keyword(s):  
Developing Countries ◽  
Air Conditioning ◽  
Cooling System ◽  
Evaporative Cooling ◽  
Ambient Air ◽  
Climatic Conditions ◽  
Individual Characteristics ◽  
Coefficient Of Performance ◽  
Air Conditioning System ◽  
Evaporative Cooling System

This study assesses the potential selection of efficient air-conditioning (AC) and cooling systems in order to avoid excess power consumption, mitigation of harmful refrigerants generated by the existing AC systems. Several varieties of active and passive air-conditioning systems i.e. heating ventilating air-conditioning (HVAC), vapor compression air-conditioning (VCAC) conventional direct evaporative cooling (DEC) and indirect evaporative cooling (IEC)  and desiccant air-conditioning (DAC) systems are under practice for the cooling and dehumidification. The storage of agricultural products mainly based on product individual characteristics i.e. respiration rate, transpiration rate and moisture content of that product. Variant ambient air conditions and the type of application are the main parameters for the choice of air-conditioning system to get optimum performance. The DAC system subsidize the coefficient of performance (COP) in humid regions, coastal ranges of developing countries e.g. Karachi and Gawadar (Pakistan) with hot humid climatic conditions. In similar way, hottest regions of the country such as Sibbi, Jacobabad and Multan perform better results when incorporates with M-cycle evaporative cooling system. Variation in ambient air conditions directly affect the cooling load and the choice of sustainable air-conditioning system

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.

A Field Study of a Low-Flow Internally Cooled/Heated Liquid Desiccant Air Conditioning System: Quasi-Steady and Transient Performance

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
Ahmed H. Abdel-Salam ◽  
Chris McNevin ◽  
Lisa Crofoot ◽  
Stephen J. Harrison ◽  
Carey J. Simonson
Keyword(s):  
Air Conditioning ◽  
Field Performance ◽  
Ambient Air ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Low Flow ◽  
Transient Field ◽  
Liquid Desiccant ◽  
Internally Cooled ◽  
Steady Performance

The field performance of a low-flow internally cooled/heated liquid desiccant air conditioning (LDAC) system is investigated in this paper. The quasi-steady performance (sensible and latent heat transfer rates, coefficient of performance (COP), and uncertainties) of the LDAC system is quantified under different ambient air conditions. A major contribution of this work is a direct comparison of the transient and quasi-steady performance of the LDAC system. This paper is the first to quantify the importance of transients and shows that, for the environmental and operating conditions in this paper, transients can be neglected when estimating the energy consumption of the LDAC system. Another major contribution of this work is the development and verification of a new method that quantifies (with acceptable uncertainties) the quasi-steady performance of a LDAC system from transient field data using average data.

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.

scholarly journals ПІДВИЩЕННЯ ЕФЕКТИВНОСТІ СИСТЕМ КОНДИЦІЮВАННЯ ПОВІТРЯ ШЛЯХОМ РОЗПОДІЛУ ТЕПЛОВОГО НАВАНТАЖЕННЯ ЗА СТУПЕНЕВИМ ПРИНЦИПОМ

2019 ◽  
pp. 49-53
Author(s):  
Євген Іванович Трушляков ◽  
Микола Іванович Радченко ◽  
Андрій Миколайович Радченко ◽  
Сергій Георгійович Фордуй ◽  
Сергій Анатолійович Кантор ◽  
...  
Keyword(s):  
Thermal Load ◽  
Air Conditioning ◽  
Rational Design ◽  
Ambient Air ◽  
Cooling Capacity ◽  
Climatic Conditions ◽  
Outlet Temperature ◽  
Thermal Loads ◽  
Air Conditioning System ◽  
Air Conditioning Systems

Maintaining the operation of refrigeration compressors in nominal or close modes by selecting a rational design thermal load and distributing it in response to the behavior of the current thermal load according to the current climatic conditions is one of the promising reserves for improving the energy efficiency of air conditioning systems, which implementation ensures maximum or close to it in the annual cooling production according to air conditioning duties. In general case, the total range of current thermal loads of any air-conditioning system includes a range of unstable loads caused by precooling of ambient air with significant fluctuations in the cooling capacity according to current climatic conditions, and a range of relatively stable cooling capacity expended for further lowering the air temperature from a certain threshold temperature to the final outlet temperature. If a range of stable thermal load can be provided within operating a conventional compressor in a mode close to nominal, then precooling the ambient air with significant fluctuations in thermal load requires adjusting the cooling capacity by using a variable speed compressor or using the excess of heat accumulated at reduced load. Such a stage principle of cooling ensures the operation of refrigerating machines matching the behavior of current thermal loads of any air-conditioning system, whether the central air conditioning system with ambient air procession in the central air conditioner or its combination with the local indoors recirculation air conditioning systems in the air-conditioning system. in essence, as combinations of subsystems – precooling of ambient air with the regulation of cooling capacity and subsequent cooling air to the mouth of the set point temperature under relatively stable thermal load.

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>

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.

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