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Solar pond powered liquid desiccant evaporative cooling

Solar pond powered liquid desiccant evaporative cooling

3.1.4 Partitioned Solar Pond (PSP): This solar pond has a similar principle as the Membrane Solar Pond [155]. In this type, two transparent partitions are installed. This idea occurred when Tabor [156] has noticed some problems during the operations of a solar pond. Bacterial and algae growth was a common problem facing most of the solar ponds. Moreover, the accumulation of dirt and dust in the pond caused a decrease in the transparency of the pond. Hence, less solar radiation absorbed. More problems such as evaporation have an effect on the salt concentration, making the top layer with high concentrations of salt [157]. In order to overcome these problems, two transparent partitions are installed one on top or few centimeters blow the surface of the pond, and the other at a depth of 1-2m. There are some disadvantages associated with the thin layer of water above the top partition. The disadvantages include evaporative cooling and reflectivity increase due to wave's movements, especially in windy sites. However, on the other hand, the reflective losses are decreased due to the lower index of refraction of water than plastics. An added advantage of installing partitions would be that the lower partition separates the insulating layer from the convective layer from the convective layer. This improves the stability of the solar pond and eases the heat extraction [139, 157].
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Overview Of Liquid Desiccant Based Indirect Evaporative Cooling System

Overview Of Liquid Desiccant Based Indirect Evaporative Cooling System

temperature small decrease in humidity effectiveness and with increase in desiccant flow rate small increase in humidity effectiveness was found. For the regenerator it was found that, water evaporation rate increases as with increase in air flow rate. Increase in desiccant temperature evaporation rate increases. For higher desiccant concentration, evaporation rate decreases. Using lithium chloride, regenerator of packed bed type studied by Min-Hwi Kim et al. [20]. Model was developed based on open literature and experimental data. For the analysis simple first order polynomial regression model was used. And this model can be used for finding most favourable regeneration temperature or desiccant flow rate in liquid desiccant system. This model approved well with experimental data and other models. Solar regenerator using liquid desiccant as calcium chloride was studied by S. Alizadeh and W. Y. Saman [21]. For variation in mass flow rate different numbers of spray nozzles was used. Experimental result shows that as the air mass flow rate increases, water evaporation from diluted solution increases. Water loss rate decreases as the solution mass flow rate increases. And regenerator thermal performance impacted by solar isolation during regeneration. The experimental results show general concurrence with results of the test executed by alternative investigators and truthful agreement with model prediction.
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Solar assisted desiccant evaporative cooling system for office buildings in Iran: a yearly simulation model

Solar assisted desiccant evaporative cooling system for office buildings in Iran: a yearly simulation model

A number of research studies on the SDCS have been reported theoretically and experimentally [7-22]. For instance, Li et al. [7] investigated the performance of two-stage desiccant cooling/heating system powered by solar energy. The study showed that the two- stage desiccant cooling system can totally handle the humidity load for 63 days (51.7%), and about 49.0% can be handled by the solar energy for seasonal total heating load. Mavroudaki et al. [8] studied the feasibil- ity of the solar powered single-stage desiccant cooling for the Europe. Based on this research, application of the system was recommended for southern Europe and most of central Europe. In another research, the application of a solar assisted heating and desiccant cooling system was examined for domestic buildings [9]. A solar assisted pre-cooled hybrid desiccant cooling system was investigated and recommended for Pakistan by Khalid et al. [10]. In this study, four modes of the cooling purposes were tested. Bourdoukan et al. [11] investigated solar desiccant plant equipped with heat pipe tubes. In another research study, the capability of a solar desiccant evaporative cooling was investigated for commercial buildings under the Australia climate
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Design and Construction of a Solar Powered Evaporative Air Cooler

Design and Construction of a Solar Powered Evaporative Air Cooler

cooler while; Figure 1.2b describes the cooling path for this type of cooling system. Its application is also worldwide and proven to be energy-saving and simple operation. [6] Presented a performance test of a direct evaporative cooler coupled with a ground circuit in Tehran. The investigation showed that the coupled system sufficiently provided the comfort condition with high cooling effectiveness and greatly reduce the electricity cost. [7] I nitiated a performance investigation of a direct evaporative cooling system powered by solar energy with photovoltaic panels in Algerian. The monitor data indicated that the largest temperature drop of supply air could reach as low as 8.86 C and almost two third of the country was installed with direct evaporative cooler due to the hot and arid climate, proving the direct evaporative cooler environmentally friendly and realistically feasible. [8] P resented an innovative model which utilizing solar assisted desiccant and direct evaporative cooling system to decrease the energy consumption of a building air conditioning system. The experimental results implied the capacity of this novel system for cooling supply air down to - C, which successfully eliminate the installation of cooling coils. Hence, the electrical energy associated with this auxiliary cooling device could be saved, resulting in increased electrical coefficient of performance (COP).
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Solar Energy as a Regeneration Heat Source in Hybrid Solid Desiccant – Vapor Compression Cooling System – A Review

Solar Energy as a Regeneration Heat Source in Hybrid Solid Desiccant – Vapor Compression Cooling System – A Review

III. WORKING OF SOLAR ASSISTED HYBRID SOLID DESICCANT – VAPOR COMPRESSION COOLING SYSTEM The integrated form of the solar powered solid desiccant – vapor compression hybrid air-conditioning commonly known as ventilation system while it makes use of fresh ventilated (outdoor) air as a process air at the dehumidifier inlet. In ventilation mode, outdoor fresh air is used as process air at dehumidifier inlet. In the process air side of the system configuration shown in Fig. 2 (J.J. Jurinak, 1982), the fresh ambient air stream (state 6) passes through various channels of rotary desiccant wheel. Its humidity is substantially lowered by the desiccant material owing to pressure difference between it and the vapor in air can be said and the heat of adsorption increases its temperature so that a dehumidified warm air stream exiting the dehumidifier (state 2). Then it is cooled successively in the heat recovery wheel (2–3), and later in vapor compression cooling coil (3–4) up to the room supply designed comfort conditions. Existing condition (state 5) within conditioned space is also shown [8]. In regeneration side, room return air (state 1) is sensibly heated by passing through heat recovery wheel, simultaneously its pre-cools pas- sing process air on the other side. This is necessary to reduce the re- generation heat consumption. So, the temperature of reactivation air is elevated while coming out from the heat recovery wheel while the humidity ratio is constant (state 7). This heated air is finally reached its reactivation temperature (state 8) by passing through liquid to air heating coil for reactivating the desiccant material used in the dehumidifier. The hot and humidified air available after the regeneration process at dehumidifier exit (state 9) is exhausted to the ambient (D.B. Jani et al, 2018).
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A critical review on evaporative desiccant cooling

A critical review on evaporative desiccant cooling

The desiccant powered evaporative cooling controls sensible and latent cooling load separately to avail thermal comfort in buildings. Against VCR based conventional cooling, this replaces compressor with rotary dehumidifier which can be regenerated with renewable solar heat or industrial waste heat to reduce consumption of electricity and emission of CO 2 remarkably. Thus, desiccant based evaporative cooling is a good option to traditional cooling

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Performance assessment of a membrane liquid desiccant dehumidification cooling system based on experimental investigations

Performance assessment of a membrane liquid desiccant dehumidification cooling system based on experimental investigations

The selection of an evaporative cooling unit for an LDDC system depends on climate condition, supply air demand, cost and etc. The feasibility of an LDDC system with an indirect evaporative cooling unit is evaluated by experimental work in [24], in which the indoor air temperature reduces from 33.8°C to 22.3°C and the relative humidity decreases from 68.6% to 35.5%. With the similar design concept, a drop of 7.5°C in the indoor air temperature is achieved in [25]. In response to the climate condition and air conditioning requirement in Hong Kong, a hybrid liquid desiccant air conditioning system is developed by integrating both direct and indirect evaporative cooling means [26], whose performance is investigated by theoretical modelling. The LDDC system with an evaporative cooling unit is proved with remarkable energy and cost saving potentials [27]. By installing an evaporative-cooling assisted LDDC system for an open office building in Seoul, South Korea, 12% saving of the annual primary energy consumption could be achieved compared with the conventional air conditioning system [28]. More than 50% of the lifetime operating cost can be saved with an LDDC system compared to the conventional air conditioning system in Singapore [29]. By utilizing renewable energy in the regeneration process, the LDDC system can be more sustainable and economical, for example the abundant solar energy. Not only solar thermal but also photovoltaic technologies can be integrated into a solar-assisted LDDC system [30]. The feasibility of a membrane-based liquid desiccant dehumidification cooling (MLDDC) system powered by solar thermal energy is proved in [31]with significant economic and environmental benefits.
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Feasibility of a solar panel-powered liquid desiccant cooling system for greenhouses

Feasibility of a solar panel-powered liquid desiccant cooling system for greenhouses

Fig. 5.1: Tree diagram showing the different types of desiccators as categorised in the literature. Later, Factor and Grossman (1980) carried out experiments with a packed column desiccator filled with Intalox saddles using monoethylene glycol and lithium bromide as liquid desiccants. They validated their experimental results against predicted ones obtained by a theoretical numerical model (counter flow configuration) which was based on Olander’s early work (1961). The LiBr results had very good agreement with the experimental ones; the average percent error was less than 8%. Longo and Gasparella (2005) investigated the performance of a packed column with random packing working as dehumidifier/regenerator using LiCl, LiBr and potassium formate. The differential model presented regarded counter flow configuration too and it was solved by an iterative procedure. The experimental dehumidification efficiency reported ranged between 30-90% approximately and the predicted values of efficiency had 8.8% mean absolute deviation when compared to the experimental results. The studies of Chengqin and his associates (Chengqin et al., 2005, Chengqin et al., 2006) also dealt with counter flow configurations. In the first study, Chengqin et al. developed a numerical model which was used to create characteristic process curves and numerical simulations were carried out under practical conditions using CaCl2 as the liquid desiccant. In the second study, a one-dimensional
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EXPERIMENTAL EVALUATION AND MODELING OF A SOLAR LIQUID DESICCANT AIR CONDITIONER

EXPERIMENTAL EVALUATION AND MODELING OF A SOLAR LIQUID DESICCANT AIR CONDITIONER

A PPHE was constructed and tested in a controlled laboratory setting, under three conditions: indirect evaporative cooing, desiccant dehumidification without internal cooling, and internally cooled desiccant dehumidification (Alizadeh and Saman, 2002). The best dehumidification performance was achieved when the dehumidifier was internally cooled and the plates were oriented at 45  . Based on the results from testing, a prototype PPHE desiccant absorber was designed and installed on an office in Brisbane, Australia with a commercial packed-bed tower regenerator (Alizadeh, 2008). A direct evaporative cooling pad was added to provide additional sensible cooling and act as a filter for the primary air stream. A 180L stratified desiccant storage tank was installed and allowed the conditioner to operate for one hour without regeneration. The conditioner was found to have a dehumidification effectiveness of 0.82 when operated with ideal air and desiccant flow rates (1000 L/s and 3 L/min respectively). Additionally, the total capacity of the system was 3.5 kW, and the electrical COP was 6. Experimental results showed good agreement with the previously developed numerical model.
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Desiccant Cooling System for Thermal Comfort: A Review

Desiccant Cooling System for Thermal Comfort: A Review

Ismail et al [38] (1991) analyzed the performance of a solar regenerated open cycle desiccant bed grain cooling system. They performed experiments on simple to build solar regenerated open cycle grain cooling system. The device consists of 95.85 m2 collector coupled with two beds of silica gel. Results from a series of experiments suggest that the device may be used to cool up to 200 tonnes of grain. The electrical power consumption of the device is of the order of 0.3 watt per tonne of grain cooled and the total electrical energy consumption is of the order of 0.7 KWH per tonne of grain stored for a 6 months period. The solar cooling devices particular effective in tropical climates. An open inclined surface forced flow and brine still solar regenerators have been analytically modeled and a comparative assessment using a numerical model has been presented. The effects of various operating and climatic parameters on the water mass desorption rate for the given working fluid have been studied.
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Comparison on cooling efficiency of cooling pad materials for evaporative cooling system

Comparison on cooling efficiency of cooling pad materials for evaporative cooling system

64 Fig. 4: (a) Side view and (b) angle view of evaporative cooling box. Two different materials namely activated carbon foam and luffa pad were tested one by one. The thickness of each type of pad is set to be 2 cm for each sheet of pad. Initially set up was run for about 10 min to ensure near steady state condition. Then dry bulb and wet bulb temperatures of air at inlet and dry bulb temperature at outlet were measured using thermocouples and recorded using data logger. The saturation effectiveness of cooling pads was calculated using the following relation as mentioned in equation (1) below:
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A novel heat recovery/desiccant cooling system

A novel heat recovery/desiccant cooling system

transfer is about 3.25% higher than the experiments results. The enthalpy recovery effectiveness of the modelling results is 2.4% lower than the experiments. 4.6.3 Reasons Causing the Differences between Simulations and Testing Results The reasons causing the differences between the test and experimental results are as follows: (1) the simulations’ pre-set conditions were the average values of the practical test conditions, which varied in a small range, and this could cause errors between the experimental and simulation results; (2) the influence of the sensible heat transfer to mass transfer considered in the simulation is not accuracy. (3) mass transfer through the liquid desiccant soaked-fibre membrane is the correction based on the clean fibre membrane, this assumption arouses errors to simulation; (4) the simulation limit accuracy could brings errors; (5) the experimental tests were carried out in the winter in the University of Nottingham, where the weather was cold and humid, and although the air ducts and boxes all had heat preservation, the weather still affected the sensor probes to some degree; (6) the air flow rates of fresh and exhaust air were measured by the thermal anemoscope, and the average values of 12 measuring points distributed at the cross section of the duct were used in calculating the recovery effectiveness, hence, there is potential to bring errors into the test results.
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Regenerated desiccant devices for cooling stored grains

Regenerated desiccant devices for cooling stored grains

that the calculated grain temperatures agree with the recorded data very well along the centerline of the silo and the more accurate methods of simulating the headspace and the wall of[r]

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Fabrication of Portable Solar Thermo Electric Refrigerator by Liquid Cooling

Fabrication of Portable Solar Thermo Electric Refrigerator by Liquid Cooling

The increase in demand for refrigeration globally in the field of air-conditioning, food preservation, medical services, vaccine storages, and for electronic components temperature control led to the production of more electricity and consequently an increase in the CO2 concentration in the atmosphere which in turn leads to global warming and many climatic changes. Thermoelectric refrigeration is a new alternative because it can reduce the use of electricity to produce cooling effect and also meet today’s energy challenges. Therefore, the need for thermoelectric refrigeration in developing countries is very high where long life and low maintenance are needed. The objectives of this study is to develop a working thermoelectric refrigerator to cool a volume of 40 L that utilizes the Peltier effect to cool and maintain a selected temperature range of 5 0C to 25 0C. The design requirements are to cool this volume to temperature within a short time and provide retention of at least next half an hour. The design and fabrication of thermoelectric refrigerator for required applications are presented.
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Financial Evaluation of Solar Powered Absorption Cooling System for Computer Laboratory

Financial Evaluation of Solar Powered Absorption Cooling System for Computer Laboratory

To plan any energy project such as solar cooling systems, economic consideration form the basis for decision making. All the cost over the entire life cycle can be grouped into three categories: capital costs, which contain the major equipment cost including installation, maintenance cost and operating cost for the cost of energy and other material inputs in the system. It is assumed that in India, there is no demolition cost. Table 2 shows the cost of the components associated with the solar thermal cooling and reference system.
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A Review of Evaporative Cooling Technologies

A Review of Evaporative Cooling Technologies

The active direct evaporative coolers are electricity-driven systems, however, it use a fraction of power for air and water circulation. So, it is considered much less energy intensive than other traditional cooling technologies, with energy saving up to 90% [3]. A typical direct evaporative cooler comprises of evaporative media (wettable and porous Pads), fan blows air through the wetted medium, water tank, recirculation pump and water distribution system, as illustrated schematically in Fig. 2a. The direct evaporative cooling is an adiabatic cooling process, i.e. the total enthalpy of the air is constant throughout the process, as shown in Fig. 2b. The water absorbs the sensible heat from the supply air and evaporates causing the air temperature decreases and its humidity to increase [4].
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Application of Solar Energy for Regeneration of liquid Desiccant Using Rotating Tilted Wick

Application of Solar Energy for Regeneration of liquid Desiccant Using Rotating Tilted Wick

energy system. Interest in utilizing solar-driven cooling systems for air-conditioning or refrigeration purposes has grown continuously. This technology, which can efficiently serve large latent loads, will greatly improve indoor air quality by allowing more ventilation as well as controlling humidity more tightly [1]. Solar energy can be used to power a solar cooling system in different ways. The solar cooling system is generally comprised of three sub-systems: the solar energy conversion system, the refrigeration system, and the cooling load. The appropriate cycle in each application depends on cooling demand, power, and the temperature levels of the refrigerated object, as well as the environment [2]. Liquid desiccants are attractive because of their operational flexibility and their capability of absorbing pollutants and bacteria. Compared to solid desiccants, they are generally regenerated at relatively lower temperature and, equally cause lower airside pressure drops. Their disadvantage is their carryover in the process air stream during the dehumidification operation. Technologically, the equipment providing air/solution contact surface (contactor) can be a wetted wall/falling film absorber, a spray chamber or a packed tower. Packed towers are subdivided into regular (structured) or irregular (random) packing ones. The liquid desiccant assisted air conditioning can achieve up to 40% of energy savings with regard to traditional air conditioning system and those savings become even greater when the energy needed for regeneration is drawn from solar energy or waste heat sources [3-5].
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DESIGN AND DEVELOPMENT OF SOLAR POWERED BLDC MOTOR OPERATED PELTIER COOLING

DESIGN AND DEVELOPMENT OF SOLAR POWERED BLDC MOTOR OPERATED PELTIER COOLING

Comparing the cost of this product with the available products in the market is solar product appeals better and affordable by common people. This solar product perfectly suited for villages, schools and offices and electrical crises facing thus an alternate to the power cut problems. It comprises of many attractive features such as usage of solar energy, cooler and cooling cabin at lower cost, BLDC motor employment for noise free operation and peltier cooling booster. It is eco-friendly and natural electricity saver. Durability of the product is more which minimizes the cost. No electricity isused for assembly consumption, so this product saves the energy and saves environment from getting polluted.
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Evaporative Cooling System for Air Conditioning

Evaporative Cooling System for Air Conditioning

Desiccants are hygroscopic in nature & hence they absorb moisture from the air by condensation of water vapour due to vapour pressure difference. Again the energy for condensation comes from warm and moist air in the form of heat energy and decreases the air temperature. Most of the researchers have used adiabatic contacting devices, but by cooling the LD (Liquid Desiccant) during the process of dehumidification, it will retain the water vapour pressure, hence allowing high concentration and low flow rate of LD [1]. It becomes weak by absorbing moisture from the surrounding hence it is necessary to regenerate the LD which is done by LD regenerator [2]. Two stage regeneration of LD can be done to improve the energy efficiency of the system and hence we can achieve techno-economical superiority [3]. Thus, using LD in direct contacting device can achieve cooling effect in an eco-friendly way for humid climates as well.
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Mobile Solar Thermo Refrigerator Design and Manufacture by Liquid Cooling

Mobile Solar Thermo Refrigerator Design and Manufacture by Liquid Cooling

We have succeeded in designing a system that meets the proposed objectives. However, we realize this system's limitations. The present design can be used to lower its temperature to a specific temperature only for light heat load. The system cannot handle load fluctuations. Before it can be released for efficient field use, extensive modifications need to be incorporated. This is one of the most advantageous projects to drive the refrigerator using low power. This project work has given us an excellent opportunity to use our limited knowledge and experience. Thermoelectric cooling is one of the key areas of interest to researchers. Some of the area's recent advances surpass some of the inherent demerits such as adverse COP. For its application, the Cascaded module architecture has set new limits. In addition, the recent breakthrough as a thermoelectric material in organic molecules ensures an excellent future for TER. Renewable energy integration as a power source can be used remotely with this refrigerator.
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