Study of water evaporation and condensation in a domestic refrigerator loaded by wet product (original) (raw)
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Air cooled condensers are mostly used condensers in the domestic refrigerators as they are widely acceptable and perform well. But its performance is depended upon the air (as a cooling medium) present around it. To increase its performance we can use evaporative cooling. This can improve the performance within the wide range of cooling. As water is used, it definitely give better results than air cooled condensers. This paper deals with implementation of evaporative condensers. This application is further used in industrial plants also.
International Journal of Mechanical and Materials Engineering, 2008
This paper presents the moisture transfer and energy losses due to moisture of household refrigerator-freezer during the closed door operation. Moisture transfer into the cabinet takes place by two ways of gasket diffusion and cabinet breathing. Experiments were conducted in the controlled chamber to investigate the effects of the ambient temperature, cabinet load, thermostat set position and open surface water pan area inside the cabinet on moisture transfer. The average gasket diffusion and cabinet breathing moisture transfer is about 4.6 kg/year and 18 kg/year respectively. In this experimental investigation, it is found that the average energy consumption of the refrigerator-freezer in kWh/day is about 2.9, 2.8, 2.8 and 2.9 due to the ambient temperature, cabinet load, thermostat set position and open surface water pan area respectively. The ambient temperature and open surface water pan area inside the cabinet have strong influence on gasket diffusion and cabinet breathing moisture transfer respectively. The extra energy consumption due to the gasket diffusion and cabinet breathing moisture transfer has been calculated and found as 1.3 kWh/year and 4.9 kWh/year respectively. The ambient temperature and cabinet load has strong influence on energy consumption compared to the thermostat setting position and open surface water pan area inside the cabinet. The average energy consumption is about 1043 kWh/year of the refrigeratorfreezer.
Journal of Energy & Environment, 2007
This paper presents the mode of moisture transport and their effect on energy consumption during open and closed door condition. Moisture can be transported into the refrigerator during closed and opening door conditions. Open door moisture transport depends on the number of door opening and duration of door remains open. The rate of moisture transport during open and closed door condition and energy consumption are calculated. The result of this study shows that the refrigerator with door openings consumes 8% more energy than the same refrigerator without door openings. The extra power consumption due to moisture transport during the period of 10 year by the refrigerators in Malaysia is calculated and found that 4% of the total energy is consumed.
Heat transfer by natural convection in domestic refrigerators
Journal of Food Engineering, 2004
This paper analyses heat transfer by natural convection in domestic unventilated refrigerators. A literature review of natural convection in an empty cavity, between vertical plates and air, and between a cylinder and air, was conducted in order to gain an insight into the mechanism of heat transfer. A model is proposed in order to quantify heat exchange by convection, conduction and radiation in a typical refrigerator; the predicted mean air temperature and refrigerating capacity are close to the experimental values. Another numerically solved model was carried out in order to estimate the time required to cool warm food which is placed inside the refrigerator. Good agreement was obtained when calculated and experimental temperatures were compared.
Performance Analysis of Domestic Refrigerator with Forced and Natural Convection
The system is not present in use due to arrangement of its various parts which are using additionally in it. In present, domestic refrigerators work on vapor compression cycle. In this cycle the heat is rejected through condenser or heat exchanger. In this way the rejection of heat occurs as a natural convection, due to this, refrigerating effect will obtain. Our modification in this system is that, if we perform through an arrangement of heat exchanger and exhaust fan the flow rate of heat should increase. Thus, in this way at same energy input the refrigerating effect may improve. Our future plan is to modify the domestic refrigerator that it could work on both natural convection and forced convection. In this way we can compare the Coefficient of performance for both processes and may do comparative study about both systems at different-different conditions.
Numerical simulation of air flow and heat transfer in domestic refrigerators
This work was carried out in order to study heat transfer by natural convection in domestic refrigerators without ventilation. Only the refrigerating compartment was studied for three configurations: empty refrigerator, refrigerator equipped with glass shelves and refrigerator loaded by product. Both experimental and numerical approaches were used.
Experimental Investigation of a Household Refrigerator Using Evaporative-Cooled Condenser
The objective of this paper was to investigate experimentally the effect of Evaporative-cooled condenser in a household refrigerator. The experiment was done using HCF134a as the refrigerant. The performance of the household refrigerator with air-cooled and Evaporative-cooled condenser was compared for different load conditions. The results indicate that the refrigerator performance had improved when evaporative-cooled condenser was used instead of air-cooled condenser on all load conditions. Evaporativecooled condenser reduced the energy consumption when compared with the air-cooled condenser. There was also an enhancement in coefficient of performance (COP) when evaporative-cooled condenser was used instead of air-cooled condenser. The Evaporative cooled heat exchanger was designed and the system was modified by retrofitting it, instead of the conventional air-cooled condenser by making drop wise condensation using water and forced circulation over the condenser. From the experimental analysis it is observed that the COP of evaporative cooled system increased by 13.44% compared to that of air cooled system. So the overall efficiency and refrigerating effect is increased. In minimum constructional, maintenance and running cost, the system is much useful for domestic purpose. This study also revealed that combining a evaporative cooled system along with conventional water cooled system under the condition that the defrost water obtained from the freezer is used for drop wise condensation over condenser and water cooled condensation of the condenser at the bottom using remaining defrost water would reduce the power consumption, work done and hence further increase in refrigerating effect of the system. The study has shown that such a system is technically feasible and economically viable
In-Situ Evaporator Heat Transfer Experiments for Domestic Refrigerators
2000
This paper describes a specially prepared experimental set-up to measure the heat transfer characteristics of evaporators placed inside a domestic refrigerator or freezer. The evaporators can either be of the forced air or natural convection type (optionally integrated into the cabinet wall). The paper discusses the special arrangements needed in this experimental set-up to accurately determine the very low heat flows occurring (from 20 to 80 W). Special attention will be paid to the refrigerant flow control needed to set a certain superheat at the evaporator outlet. It will be shown that the same apparatus can also be used to measure the heat transmission through the cabinet walls. Trial experiments, in which the radiation coefficients of the cabinet walls were varied, influencing the heat transmission coefficients, give an example of the capabilities ofthe system.
Renewable Energy, 2009
In this study, an innovative, evaporative condenser for residential refrigerator was introduced. A vapor compression cycle incorporating the proposed evaporative condenser was tested to evaluate the cycle performance. To allow for evaporative cooling, sheets of cloth were wrapped around condenser to suck the water from a water basin by capillary effect. The thermal properties at the different points of the refrigeration cycle were measured for typical operating conditions. The experimental results showed that the condenser temperature increases 0.45 C for each degree increase in evaporator temperature when the air velocity is 2.5 m/s, and the ambient condition is 29 C and the relative humidity is 37.5%. Meanwhile, the condenser temperature increase is 0.88 C in the case of air velocity 1.1 m/s and ambient conditions of 31 C and relative humidity of 47.1%. A theoretical model for the evaporative condenser was developed, and validated by experimental results. The theoretical model showed that the evaporative condenser can operate at a condensing temperature of 20 C lower than that of the air-cooled condenser for heat flux of 150 W/m 2 , and at air velocity 3 m/s. The effect of the different parameters on the condenser temperature was studied too.
Journal of Food Engineering, 2008
An experiment was carried out using a refrigerator model in which heat is transferred by natural convection. This transfer takes place between a cold vertical wall and the other walls, which are exposed to heat losses. The air velocity measurements were undertaken using particle image velocimetry (PIV). Circular airflow was observed in the cavity: air flows downward along the cold wall and upward along the other walls. The maximum air velocity (0.2 m/s) was observed near the bottom of the cold wall. Non-stationary airflow with recirculation was observed along the horizontal bottom wall of the cavity. Airflow is very weak (<0.04 m/s) at the central zone and it is quasistagnant at the top. The velocity profile in the boundary layers of the empty refrigerator model was also investigated. The influence of temperature and surface area of the cold wall on air velocity were studied. It was found that the influence of the cold wall temperature on the air velocity is more significant than the surface area. In order to study the effect of obstacles on velocity profiles, the refrigerator model was filled with four blocks of hollow spheres. The air velocity in the case of filled refrigerator was compared with the results of the empty one. The air velocity is lower almost everywhere in the filled refrigerator model. The presence of the blocks seems to homogenise the air velocity.