scholarly journals Experimental Research on Regeneration Characteristic of ED Regeneration for Lithium Bromide Desiccant Solution with High Concentration: Operating Condition and Electrode Solution

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4733
Author(s):  
Qing Cheng ◽  
Han Wang
Keyword(s):  
Flow Rate ◽  
Air Conditioning ◽  
Lithium Bromide ◽  
Solution Concentration ◽  
Regeneration System ◽  
High Concentration ◽  
Air Conditioning System ◽  
Initial Concentration ◽  
Libr Solution ◽  
Short Time

Electrodialysis is regarded as a novel liquid regeneration method, and the regenerated solution can satisfy the dehumidification requirements even in a hot and humid environment. LiBr solution is an important choice for a liquid desiccant air conditioning system due to its great dehumidifying ability, so it is necessary to conduct experimental exploration of the regeneration characteristics of ED regeneration for LiBr solution. In this paper, the effects of solution concentration, circulation flow rate, current and electrode solution on the performance of the electrodialysis regeneration system were studied by constructing an experimental electrodialysis regeneration system. The results show that growing the starting concentration of the LiBr solution adversely affects the regeneration characteristics of the electrodialyzer and of the air conditioning system dehumidified by the solution. Under test conditions, as the initial concentration of LiBr solution increased from 45% to 55%, the performance coefficient (COP) of the system decreased from 2.12 to 1.05. When the dehumidification requirement is met, the initial concentration of the LiBr solution should be reduced. Increasing the circulating flow rate can improve the regeneration performance of the electrodialyzer and the capability of the air conditioning system dehumidified by the solution, but excessively increasing the circulating flow rate will decrease the regeneration performance of the electrodialyzer and the performance of the air conditioning system dehumidified by the solution. Increasing the current can increase the concentration of the LiBr solution in the regeneration cells in a short time, but it will reduce the regeneration performance of the electrodialyzer and the characteristic of the air conditioning system dehumidified by the solution. The current needs to be minimized when meeting regeneration requirements. With the growth in the flow rate of the electrode solution, the regeneration performance of the electrodialyser decreases continuously.

The study of solar absorption air-conditioning systems

2005 ◽  
Vol 16 (4) ◽  
pp. 59-66 ◽  
Author(s):  
V Mittal ◽  
KS Kasana ◽  
NS Thakur
Keyword(s):  
Air Conditioning ◽  
Lithium Bromide ◽  
Cooling Systems ◽  
Solar Absorption ◽  
Air Conditioning System ◽  
Heating And Cooling ◽  
Absorption Cooling ◽  
Solar Powered ◽  
Solar Absorption Cooling ◽  
Air Conditioning Systems

An air-conditioning system utilizing solar energy would generally be more efficient, cost wise, if it was used to provide both heating and cooling requirements in the building it serves. Various solar powered heating systems have been tested extensively, but solar powered air conditioning systems have received very little attention. Solar powered absorption cooling systems can serve both heating and cooling requirements in the building it serves. Many researchers have studied the solar absorption air conditioning system in order to make it economically and technically viable. But still, much more research in this area is needed. This paper will help many researchers working in this area and provide them with fundamental knowledge on absorption systems, and a detailed review on the past efforts in the field of solar absorption cooling systems with the absorption pair of lithium-bromide and water. This knowledge will help them to start the parametric study in order to investigate the influence of key parameters on the overall system performance.

scholarly journals Performance optimization of polymeric porous membrane-based liquid desiccant air dehumidifier used in air conditioning system

2019 ◽  
Vol 11 (1) ◽  
pp. 55-71
Author(s):  
Ali Mohammad Jafarpour ◽  
Farivar Fazelpour ◽  
Seyyed Abbas Mousavi
Keyword(s):  
Performance Optimization ◽  
Air Conditioning ◽  
Weather Conditions ◽  
Porous Membrane ◽  
Operating Conditions ◽  
Regeneration System ◽  
Liquid Desiccant ◽  
Air Conditioning System ◽  
Air Stream ◽  
Improved Performance

AbstractIn this study an experimental design was developed to optimize the performance and structure of a membrane-based parallel-plate liquid desiccant dehumidifier used in air conditioning regeneration system which operates under high humidity weather conditions. We conducted a series of polymeric porous membranes with different compositions fabricated that were prepared with various weight percentages of polysulfone (PSU), mixed with N-methyl-2-pyrrolidone (NMP) and dimethyl form amide (DMF) solvents. Furthermore, the designed experiments were performed under various operating conditions, indicating that the dehumidification efficiency declines with increasing flow rate, temperature, and humidity. Consequently, a membrane with optimized porosity and moisture permeability was selected which resulted in eliminating the carryover of solution droplets in the air, largely due to separating the flow condition of liquid desiccant (Li Cl) and air. This specific design is also greatly benefited by removing the water vapor from the air stream. The results of mathematical model simulations indicate that the DMF solvent had higher dehumidification capability compared with that of NMP under the optimized operating conditions. Additionally, it can clarify the porosity of the membrane which plays a significant role in the overall performance. Therefore, the fabricated membrane produces fresh cool air, and it can be applied as a guiding sample for designing the membrane-based dehumidifier with improved performance.

An Analysis of a Direct Radiation Solar Dehumidification System

1987 ◽  
Vol 109 (1) ◽  
pp. 15-21 ◽  
Author(s):  
K. Schultz ◽  
R. Barlow ◽  
A. Pesaran ◽  
F. Kreith
Keyword(s):  
Heat Exchanger ◽  
Numerical Model ◽  
Solar Radiation ◽  
Air Conditioning ◽  
Direct Solar Radiation ◽  
Direct Absorption ◽  
Ventilation Mode ◽  
Regeneration System ◽  
Air Conditioning System ◽  
Direct Radiation

A desiccant dehumidifier regenerated by direct absorption of solar radiation was investigated using a simplified numerical model (DESSIM) of the adsorpotion and desorption processes. This paper presents estimates of the performance of an air conditioning system in the ventilation mode using direct solar radiation regeneration. The effects of dehumidifier NTUs, heat exchanger performance, and insolation levels were also analyzed. The direct radiation regeneration system was found to have a COP less than that of other types of regeneration schemes.

Flow Resistance Coefficient Identification of Chilled Water System Based on Multi-Objective Optimization and Experiment Validation

2014 ◽  
Vol 651-653 ◽  
pp. 742-746
Author(s):  
Zhi Jian Hou ◽  
Ming Qu ◽  
Zhi Rui Wang
Keyword(s):  
Flow Rate ◽  
Air Conditioning ◽  
Optimization Problems ◽  
Water Flow Rate ◽  
Resistance Coefficient ◽  
Fundamental Parameter ◽  
Multi Objective Optimization ◽  
Air Conditioning System ◽  
Multi Objective ◽  
Terminal Unit

Hydraulic resistance coefficient (HRC) is a fundamental parameter that characterizes the hydraulic state of a water pipeline and significantly determines the efficiency of the water-transport process. To estimate HRC and diagnose hydraulic process fault in building air conditioning system, a novel method called multi-objective optimization (MBO) strategy was developed in the research effort. MBO is concerned with mathematical optimization problems involving more than one objective function to be optimized simultaneously. In this paper, first, the basic principle of the approach is presented. Then several experiments are conducted to identify the HRC in a real air conditioning system. And the water flow rate of each air handling terminal unit is estimated by the flow rate of primary pipe and identified HRC. The experiment results show that the model can accurately estimate HRCs. The HRCs of each pipe and terminal unit were obtained by the flow rate and the pressure difference of primary pipe without requiring geometric specifications, which is very convenient in real engineering application.

Effect of Condenser Temperature and Speed on one A/C System

2011 ◽  
Vol 314-316 ◽  
pp. 686-690
Author(s):  
Cheng Jun Pan ◽  
Yi Da Tang
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Air Conditioning ◽  
Systems Design ◽  
Test System ◽  
Coefficient Of Performance ◽  
Two Phase ◽  
Flow Measurements ◽  
Air Conditioning System

This study describes the results on the performance of one vehicle air conditioning system. The coefficient of performance, evaporator cooling capacity, compressor power consumption, total mass flow rate, vapor mass flow rate, liquid mass flow rate and oil in circulation, pressures and temperatures of refrigerant at every component (inlets and outlets) are measured and analyzed with the variation of the outside temperatures at the evaporator and condenser, the speed of the compressor, refrigerant charge and oil charge. The systematical experimental results obtained from this real-size test system depict the relations between the above parameters in a vehicle air conditioning system, which constitute a useful source for vehicle air conditioning systems design and analysis. The vapor quality (two-phase flow) measurements realized in this work provide an extremely important tool for diagnosing the system performances.

Solar Air Conditioning Systems With PCM Solar Collectors

Solar Energy ◽  
2002 ◽  
Author(s):  
Jorge E. Gonza´lez ◽  
Luis Humberto Alva S.
Keyword(s):  
Flat Plate ◽  
Thermal Performance ◽  
Air Conditioning ◽  
Lithium Bromide ◽  
Geographical Location ◽  
Solar Collectors ◽  
Absorption System ◽  
Air Conditioning System ◽  
Graphite Composite ◽  
Cooling Loads

This paper investigates the technical feasibility of using a compact, air-cooled, solar absorption air conditioning system when coupled to an innovative array of solar collectors. The particular absorption system of study is a single effect that uses lithium bromide and water as the absorbent and refrigerant fluid pair. The geographical location of interest is Puerto Rico and similar subtropical regions. The heat input to the absorption system generator is provided by an array of novels flat plate solar collectors that integrate the thermal storage component into them. The proposed collectors have a phase change material (PCM) integrated into them as a storage mechanism. The PCM-integrated solar collector eliminates the need of conventional storage tanks reducing cost and space. The present work uses a paraffin-graphite composite as the PCM to increase the conductivity of the PC matrix. The paraffin’s melting point is around 89°C that is appropriate for use in absorption systems. The mathematical model that describes the thermal process in the PCM is presented and differs from the analysis of conventional flat plate solar collectors. The proposed model for the PCM considers the temporal changes but not the spatial variations. The resulting set of equations for the fluid flow, the PCM, and the collector’s surface are solved simultaneously. Results for the collectors’ thermal performance are presented along with the effects of the composition of the PCM material. The thermal performance of an absorption machine coupled to an array of the proposed PCM’s solar collectors was investigated for nominal cooling capacities of 10.5, 14, and 17.5 kW. These cooling loads are suitable for a typical house or a small business building in Caribbean Islands. Computer simulations were conducted to evaluate the overall system’s performance when subjected to dynamic cooling loads. Within the computer model, heat and mass balances are conducted on each component of the system, including the solar collectors, the air-cooled condenser, and the air-cooled absorber. Comparisons are made with an absorption air conditioning system that uses a cooling tower with conventional flat plate collectors instead of air-cooled and PCM components. Useful information about physical dimensions of collectors, number of collectors needed, and efficiency of the overall system is presented.

scholarly journals Type and Density of Bacterial and Fungal Bioaerosols and Particles in Inside and Outside of Hospital: Modeling of Dispersion and Antibiotic Resistance of Bacterial Bioaerosols

2021 ◽  
Author(s):  
Ameneh Yousefzadeh ◽  
Afshin Maleki ◽  
Saeed Dehestani Athar ◽  
Ebrahim Darvishi ◽  
Manochehr Ahmadi ◽  
...  
Keyword(s):  
International Organizations ◽  
Air Conditioning ◽  
Loading Rate ◽  
Optimal Conditions ◽  
High Concentration ◽  
Air Conditioning System ◽  
Molecular Tests ◽  
Counter Model ◽  
Identification Of Fungi ◽  
General Average

Abstract The study of loading rate of microorganisms in the space of hospital inside and outside to evaluate their impacts on physical health of patients and staff, as well as to find out the source of possible infections and allergies stemming from the presence of bioaerosols is of great importance. In total, 262 bacterial and fungal samples were collected from the air of the wards of Tohid Hospital, Sanandaj, Iran. Also, suspended particles were measured by Particle Mass Counter (model: TES-5200). Parameter such as relative humidity and temperature were recorded by using TES-5200 device. To identify bacteria, some biochemical and molecular tests were conducted. And, for the identification of fungi, microscopic and macroscopic characteristics were used. The highest and lowest densities of the bioaerosols were observed in lung and operating wards (336.67 and 15.25 CFU/m3). Moreover, the highest and least concentrations of particles were seen in the emergency and operating wards, respectively. The most common fungi isolated from the hospital air were Penicillium (24.7%), Cladosporium (23. 4%), Aspergillus niger (13.3%) and Aspergillus Flavus (11.4%). Furthermore, the highest concentration of the isolated bacterium was Staphylococcus hemolyticus (31.84%). And, the bacteria had the most resistance to antibiotic gentamicin.The general average of air pollution of the hospital to bioaerosols in quantitative terms was higher than that suggested by international organizations. Considering the high concentration of bioaerosols and particles in the hospital studied, provision of optimal conditions (like temperature, humidity, suitable ventilation and intelligent air conditioning system) and imposing a restriction in the entrance of the wards can be utilized to reduce the amount of pollution.

Evaluation of membrane-based air pre-dehumidification for a capillary radiant air conditioning system

2020 ◽  
pp. 1420326X2096738
Author(s):  
Zan-She Wang ◽  
Fang-Ting Yin ◽  
Ran Li ◽  
Zhao-Lin Gu
Keyword(s):  
Moisture Content ◽  
Air Conditioning ◽  
Dew Point ◽  
Liquid Desiccant ◽  
Air Conditioning System ◽  
Point Temperature ◽  
Dew Point Temperature ◽  
Temperature Range ◽  
Libr Solution ◽  
The Ideal

The polyvinylidene fluoride hollow fibre membrane air dehumidification tests were carried out between the liquid desiccant solutions and the wet air. Three liquid desiccant solutions of LiBr solution (50%), LiCl solution (35%) and CaCl2 solution (40%) were tested under different wet air conditions. The results showed that all the membrane dehumidification processes were stable. The air moisture content in the outlet of the membrane was maintained as 6.5 g/kg (da)–8.2 g/kg (da) when the air moisture content in the inlet of the membrane was operated from 17.1 g/kg (da) to 32.4 g/kg (da). The dehumidification amount of LiBr solution (50%) and LiCl solution (35%) was more productive. On this basis, a membrane-based air pre-dehumidification process for the capillary radiant air conditioning system was built. Since the ideal dew point temperature range of the indoor air is below 14–17°C according to the cold supply water, all the air moisture content at the membrane outlet is much lower than that of the ideal dew point temperature range, which means non-condensing occurs in the capillary tube surface. The membrane-based air pre-dehumidification process can easily form an adaptive regulation process of humidity with the capillary radiant air conditioning system under different environmental parameters.

Photovoltaic Driven Liquid Dehumidification Air-Conditioning System

2013 ◽  
Vol 805-806 ◽  
pp. 125-130
Author(s):  
Xiu Wei Li ◽  
Xiao Song Zhang ◽  
Qing Cheng
Keyword(s):  
Air Conditioning ◽  
Electric Energy ◽  
Coefficient Of Performance ◽  
Low Grade ◽  
Power Performance ◽  
Air Conditioning System ◽  
Libr Solution ◽  
Driven System ◽  
Low Grade Heat ◽  
Vapour Compression

Liquid dehumidification air-conditioning system is a promising air-conditioning system as it is environment-friendly, capable of utilizing low grade heat and less dependent on the electric power. However, because of the heat waste, its performance is not yet as competitive as vapour compression system. To improve, a photovoltaic driven system is proposed in this paper: electricity is applied to regenerate desiccant; the electric energy comes from solar power. Performance analysis has been made. The results show the coefficient of performance of the new system is influenced by the concentration of the desiccant and can approach 6 at certain circumstances. It also shows that LiBr solution is more favorable among three common used desiccants. Moreover, this paper presents the new progress of experimental research on this system.

Sign in / Sign up

Export Citation Format

Share Document