Transient analysis and performance prediction of a solid adsorption solar refrigerator (original) (raw)
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Model performance assessment and experimental analysis of a solar assisted cooling system
Solar Energy, 2017
Due to the economic development and occupancy requests, building thermal comfort reached higher levels during the last years. Energy consumption rates have become excessive and engendered an increasing reliance on fossil-fuel reserves. Hence, the conception of energy-efficient buildings as well as applying solar cooling techniques has become a promising solution. In this context, the current work dealt with the appraisal of a solar system that drives the cooling process in an office building located in the Center of Researches and Energy Technologies in Tunisia. The solar system consisting of linear parabolic trough solar collectors' field coupled to a 16 kW double effect Lithium Bromide absorption chiller, supplies chilled water to a set of fan coils installed in the 126 m 2 laboratory building. A dynamic model that couples the solar cooling system with the building was developed using the TRNSYS tool and several simulations were performed to assess the case study and improve its performance. The model results were compared to the data collected during the experimental campaign conducted in summer 2015 and showed that the collectors efficiency was at the range of 26-35%, the COP ranged between 0.65 and 1.29, the daily maximum solar COP was approximately at 35%. However, the solar system was unable to cover 32.3% of the cooling requirements, the absorption chiller was switched on only during 53.8% of its total operating time. An improved system configuration was then studied; the integration of an auxiliary heater prior to the chiller as well as the increase of the aperture area guaranteed high driving temperatures and more suitable conditions to the absorption chiller. As a result, the chiller operating time increased to 75.8%, the cooling power increased by 75.6%, the solar COP reaches 57% and the solar fraction averaged 87%. The summer season performances predict that the improved system configuration achieves primary energy savings that reach 82.3% compared to a classic air conditioning system producing the same cooling power, the yearly avoided CO 2 emissions are estimated to 2947 kg.
During the last twenty years, the comfort and cooling requirements of office buildings and occupants have evolved significantly in Reunion Island, particularly during the summer period. This intensive use of air conditioning has resulted in a significant increase in electricity consumption such as traditional cooling technologies (mechanical vapor compression systems). In this context, solar cooling systems are one of the more interesting alternatives to conventional air conditioning systems. Thus in 2008, the PIMENT laboratory in Reunion Island proposed to set up an experimental platform called "RAFSOL", on the University Institute of Technology of Saint-Pierre, to study the absorption solar cooling technology for a University building. Experimental and numerical investigations of RAFSOL allowed to identify several research topics to improve global performances of the installation. One of them concerns the incorporation of a new thermal storage into the solar cooling syst...
A passive cooling system of residential and commercial buildings in summer or hot season
IOP Conference Series: Materials Science and Engineering, 2015
The demand of ventilation appliances in the residential and commercial buildings in the topical reason is increasing very rapidly due to the population increase as well as climate change. The increasing number of high rise buildings may result in the lack of natural ventilation in modern buildings. Generally, fan and air conditioning are used in the modern building for cooling as well as for air ventilation. In the tropical regions most of the energy is consumed by the heating, cooling and ventilation appliances.Therefore, solar power appliance for cooling, heating and ventilation will be a suitable and valid option for the saving of energy from the household sector.A modified-structure building is designed and constructed with solar chimney to enhance ventilation rate that increases cooling performance as well as ensuring thermal comfort. An evaporative cooler is introduced with newly designed room to enhance the temperature reduction capacity. The room temperature is compared with a non-modified room as well as with ambient temperature. The results show that passive cooling system with evaporative cooler was able to reduce temperature by 5°C compared to the ambient temperature and about 2˚C to 3˚C below the reference room temperature.
IJERT-Analysis Of Solar Absorption Cooling System For Domestic Applications
International Journal of Engineering Research and Technology (IJERT), 2012
https://www.ijert.org/analysis-of-solar-absorption-cooling-system-for-domestic-applications https://www.ijert.org/research/analysis-of-solar-absorption-cooling-system-for-domestic-applications-IJERTV1IS9231.pdf The increase in demand of airconditioning has significantly increased the electricity consumption of the building. The conventional vapor compression system is main cause of high electricity consumption. The residential building has large percentage of this consumption. The high energy consumption and limited sources, leads the world to energy shortage. The solar airconditioning system is a good replacement of conventional airconditioning system. There are various types of solar cooling technologies namely solar photovoltaic, desiccant cooling adsorption and absorption cooling system. For residential building at New Delhi, India. Solar absorption cooling system is developed and simulated in TRNSYS with three types of solar collectors namely E.T.C, F.P.C and P.T.C. The parameter storage tank volumes and flow rate are used to study the performance of solar cooling system. 0.86 m 3 chilled water storage tank and 6.72 m 3 hot water storage tank combinations is best in all configurations with the 5372 kg/hr Chilled Water Flow Rate to cooling coil.
Numerical simulation of combined solar passive heating and radiative cooling for a building
While solar energy can be utilized for passive space heating, efficient passive space cooling is achievable through lower temperature ambient thermal sources. In this study, a model was proposed for the combined solar heating and radiative cooling and a MATLAB code is developed to simulate combined space heating and cooling of a small building in Louisville, Kentucky. The combined system consists of the glazing/transparent insulation subsystem and the thermal storage subsystem. The space is passively heated and cooled by means of natural convection from the surfaces of the storage subsystem where the storage tank is heated by solar radiation and cooled by night sky radiation as a low temperature thermal source. The model for this system consists of several transient energy balance equations based on the lumped capacitance approach and it has been implemented utilizing MATLAB. Using the aforementioned system and the auxiliary heating/cooling units, the room temperature can be kept within the prescribed comfort range. The simulation is carried out to find the monthly and annual solar fraction, required heating demand, auxiliary heating demand as well as the unwanted heat gain during heating months. Also, the radiative cooling fraction, required cooling demand and auxiliary cooling demand during cooling months are obtained. The optimum value for transparent layer absorptivity was found to avoid unwanted heat gain. Parametric sensitivity was evaluated for material and design features related to the combined system. Simulation results for temperature profiles of the room and storage tank are also illustrated.
Investigation of a hybrid system of nocturnal radiative cooling and direct evaporative cooling
Building and Environment, 2010
In this paper, the results of a study on a hybrid system of nocturnal radiative cooling, cooling coil, and direct evaporative cooling in Tehran have been discussed. During a night, the nocturnal radiative cooling provides required chilled water for a cooling coil unit. The cold water is stored in a storage tank. During eight working hours of the next day, hot outdoor air is pre-cooled by means of the cooling coil unit and then it enters a direct evaporative cooling unit. In this period, temperature variation of the conditioned air is investigated. This hybrid system complements direct evaporative cooling as if it consumes low energy to provide cold water and is able to fulfill the comfort condition whereas direct evaporative alone is not able to provide summer comfort condition. The results obtained demonstrate that overall effectiveness of hybrid system is more than 100%. Thus, this environmentally clean and energy efficient system can be considered as an alternative to the mechanical vapor compression systems.
2016
A novel HVAC system combining natural ventilation with diffuse ceiling inlet and thermally activated building systems (TABS) has the ability to fulfill the requirements of cooling and ventilation in future Danish office buildings. In order to study the cooling performance of this system, a test chamber is constructed in a way to represent the characteristics of an office room. Twenty cases are tested under steady-state conditions, including ten cases without ceiling panel and ten cases with ceiling panel. An energy balance analysis shows that the tests have quite good accuracy, with an error of less than 10%. Both the cooling capacity of TABS and the influence of ceiling panel are investigated. The U-value of TABS water side to the room side is almost constant, but the effectiveness of TABS decreases with log mean temperature difference (LMTD) for both cases with and without ceiling panel. The radiant heat transfer coefficient of TABS is reduced by the ceiling panel whereas the convective heat transfer coefficient increases with the ventilation rate and the inlet air temperature. Experimental data is used to evaluate the thermal performance of this system, and it is also beneficial to the design of this system.
The optimization of mechanical night cooling system in an office building
2006
The need of optimization for the mechanical night cooling system was discussed in many cases. The paper deals with the use of computer simulations both for the design support of a new building and HVAC system development and for the optimization of the system control strategy in the finished building. In early design of a new commercial building in Prague computer simulations were carried out to prove possible effects of night cooling ventilation. Predictions of the indoor environment and energy consumption for optional solutions regarding cooling capacities and different rates of ventilation by outdoor air helped to design an airconditioning system, which comprises of daytime top cooling and night ventilation by outdoor air combined with accumulation of cold in building constructions. Long-time monitoring and further computer simulations were performed in order to optimize the control strategy for the top cooling system.
This study indicates the analysis of the weather data effect on a small building cooled by direct solar adsorption air-conditioning system. The weather data of Malaysia was used in the simulation, with a cooling load and its variation due to the solar radiation change. TRNSYS simulation was used in this study with the assistance of HAP 4.6 software. With a cooling capacity of 3.5 kW for the adsorption system, the maximum cooling load recorded was 3.1 kW. The results of the study show that the weather data plays a major rule on the cooling load and the performance of the adsorption cooling system.