Showing 7 results for Cooling System
Q. Dorosti, M. Maerefat, A. Omidvar,
Volume 10, Issue 3 (12-2010)
Abstract
- The effect of panel height on performance of ceiling radiant cooling system has been studied. Investigation has been done by employing solution of conservative equations, together with the radiant and thermal comfort equations. Calculation is performed for the typical hottest day of Tehran. Vapour condensation is one of the most important problems whit these systems. Therefore effect of panel height on condensation has been also studied, in a residential place with several different ranges of ventilation rate. The results show that appropriate design of the panel height can significantly reduce the rate of condensation.
Mohsen Fallah, ,
Volume 11, Issue 4 (9-2011)
Abstract
In this study, the potential of controlling engine cooling temperature has been investigated experimentally to reduce NOx emissions in heavy diesel engines. Experiments have been done on 90°C and 70°C cooling temperatures that lower temperature obtained via larger radiator and setting its thermostatic valve. Also, the effects of injection timing and the percentage cooled EGR simultaneously have been studied in order to trade-off NOx reduction and increasing other pollutants such as Soot, CO, HC and fuel economy. Experimental results which related to amount of pollutants and fuel consumption by altering the engine cooling temperature, injection timing, and the percentage of cold EGR shows that NOx emissions reduce 17% averagely also fuel consumption decreases negligible.
Seyyed Behzad Golparvar, Milad Mohammadzadeh Kowsari, Hamid Niazmand,
Volume 16, Issue 8 (10-2016)
Abstract
Large amount of diesel engine waste heats make researchers design systems that utilize the engine waste heat to provide the cooling demand of the heavy-duty vehicles and improve the engine efficiency. Considerable advantages of adsorption cooling system lead to be nominated for this purpose. Coolant and exhaust gases are the main sources of waste heats of diesel engines and using each of them to drive the adsorption cooling system requires its own equipment and working pair. In this paper, a detailed numerical model has been developed and to examine the performance of the cooling system driven by the coolant waste heat with working pair of silica gel-water and also driven by exhaust waste heat with zeolite13x-water working pair. An identical absorbent bed and ambient conditions have been employed to compare the performance of both systems to identify the more appropriate system. The results show that exhaust driven adsorption cooling system has more capability to meet the vehicle cooling demand. Moreover, the performance of the both adsorption cooling systems were examined under variable ambient condition. Results indicate that increase in ambient temperature leads to almost a linear performance drop in both systems that is more considerable in the coolant- driven adsorption system.
Mehdi Maerefat, Asgar Minaei,
Volume 16, Issue 10 (1-2017)
Abstract
In the present study, the direct utilization of borehole as a heat sink for both residential and office building is investigated in Tabriz city. The effect of external wall insulation and windows glazing is studied in the form of four cases and the performance of the ground sink direct cooling system is investigated for these cases. The borehole design depth is calculated by analytical method. Both sample residential and office buildings are investigated. The borehole design depth depends on the quality of the building design and its heat emission. The results show that using double glazed windows, compared to single glazed windows reduces the borehole design depth by about 10 percent. Also the utilization of insulation in external walls and roof decreases the borehole design depth more than half compared to buildings without insulation. Finally, the potential of the ground sink direct cooling in sample residential and office buildings is investigated for four cases. The results show that by using ground sink direct cooling system, thermal comfort is satisfied in almost all of the cooling hours in both sample residential and office buildings.
Seyyed Behzad Golparvar, Milad Mohammadzadeh Kowsari, Hamid Niazmand,
Volume 16, Issue 12 (2-2017)
Abstract
The considerable amount of internal combustion engine waste heat through exhaust gases and the capability of adsorption cooling system to be driven by waste heats cause adsorption cooling systems to be interesting for vehicle air conditioning. Low specific cooling power of these systems leads them to be bulkier with respect to other cooling systems. Therefore, practical use of these system has been a challenge. One of the methods to enhance the system performance is adsorber bed optimization which is only feasible by numerical simulations. Hence, an exhaust waste heat driven adsorption cooling system with longitudinal finned-tube adsorber is simulated three dimensionally and considering heat and mass transfer details. Also, both the intra-particle and inter-particle mass transfer resistance has been taken into account in governing equations in order to study the effect of adsorbent particle diameter on the system performance. Results show that among the examined geometrical configurations, bed with 20 fin numbers and fin height of 10 mm is the optimum case corresponding to the maximum specific cooling power. In addition, adsorbent particle diameter in the range of 0.3-0.4 mm is the most suitable diameter for the adsorber bed packed with zeolite13x grains.
H. Azarkish,
Volume 19, Issue 6 (6-2019)
Abstract
In the present work, a novel configuration is proposed to improve the cooling performance of a capillary-driven system. In this approach, the possibility of meniscus formation inside the is increased for a wide range of operating temperature by controlling the capillary and viscous forces. The proposed consists of three sections. The first section is a narrow part of to control the pressure drop. The second section of is an evaporator. The meniscus is formed in this section due to of the capillary and viscous forces. It can move along the The third section is a wide part of The meniscus cannot move further in this section due to decreasing the capillary pressure. The evaporation rate from meniscus is estimated by using the thin film evaporation theory. Results show that the heat flux up to 30-100 W/cm2 70-100⁰C) can be dissipated by the evaporation mechanism from a hydrophilic membrane.
N. Sahraiyan, S.m.h. Mohammadi, E. Jahanshahi Javaran,
Volume 20, Issue 2 (1-2020)
Abstract
The application of solar energy for space cooling has been increasingly considered in Iran and other countries in the last two decades. In this study, two different configurations of a solar assisted refrigeration system have been studied. The first system is the combination of a lithium bromide vapor absorption refrigeration system and flat plate collectors. The other system is consisted of a compression refrigeration system and thermal photovoltaic panels. For this purpose, 32% of the roof area of the building has been covered with 105 flat plate collectors, each with a total area of 1.591 m2, or 288 photovoltaic panels each with an area of 0.556 m2. Both systems have been compared in terms of energy, exergy, and economic viewpoints. This comparison has been conducted for providing the 70 kW cooling capacity system required for an office building with an area of 500 m2. The results of this study showed that at an evaporator temperature of 5°C and the ambient temperature of 27°C, the coefficient of performance of the compression chiller is 3.5 and the absorption chiller is 0.71. Also, the total energy efficiency and the total exergy efficiency in the compression chiller system combined with thermal photovoltaic panels are 7.43% and 8.25% respectively. Those two parameters for the absorption chiller combined with flat plate collectors are 9.16% and 6.66%, respectively. In the economic analysis, the annual life cycle cost for the compression chiller system combined with thermal photovoltaic collectors is 9710 $ and this cost for the absorption chiller system combined with flat plate collectors is estimated 7649 $.
