scholarly journals Investigação experimental em escala reduzida sobre o uso de telhas cerâmicas como sistema de resfriamento evaporativo

Author(s):  
Marcelo Paes De Barros

<p>The present paper describes an experiment that clarifies the cooling effects of the constructed system. Tested in the Cuiabá, MT, environment, the system’s performance,, which works on the evaporative cooling principle made for this study using clay roof tiles was checked in terms of temperature drop and humidity rise air which passes through the system to the surroundings. The result showed that the cooling effect reached a maximum of 3.5 °C and increased the relative humidity of incoming air around 10%. The reduced-scale experiment has reached the appropriate temperature and humidity for air conditioning under human environmental comfort conditions in hot and dry climatic conditions, in 86.4% of the measurement periods. The use of porous ceramics as an evaporative cooling system offers the advantage of the integration into building elements.</p>

2017 ◽  
Vol 2 (1) ◽  
pp. 76 ◽  
Author(s):  
Muhammad Kashif ◽  
Muhammad Sultan ◽  
Zahid Mahmood Khan

This study assesses the potential selection of efficient air-conditioning (AC) and cooling systems in order to avoid excess power consumption, mitigation of harmful refrigerants generated by the existing AC systems. Several varieties of active and passive air-conditioning systems i.e. heating ventilating air-conditioning (HVAC), vapor compression air-conditioning (VCAC) conventional direct evaporative cooling (DEC) and indirect evaporative cooling (IEC)  and desiccant air-conditioning (DAC) systems are under practice for the cooling and dehumidification. The storage of agricultural products mainly based on product individual characteristics i.e. respiration rate, transpiration rate and moisture content of that product. Variant ambient air conditions and the type of application are the main parameters for the choice of air-conditioning system to get optimum performance. The DAC system subsidize the coefficient of performance (COP) in humid regions, coastal ranges of developing countries e.g. Karachi and Gawadar (Pakistan) with hot humid climatic conditions. In similar way, hottest regions of the country such as Sibbi, Jacobabad and Multan perform better results when incorporates with M-cycle evaporative cooling system. Variation in ambient air conditions directly affect the cooling load and the choice of sustainable air-conditioning system


Author(s):  
I Nyoman Suprapta Winaya ◽  
Hendra Wijaksana ◽  
Made Sucipta ◽  
Ainul Ghurri

The high energy consumption of compressor based cooling system has prompted the researchers to study and develop non-compressor based cooling system that less energy consumption, less environment damaging but still has high enough cooling performances. Indirect and semi indirect evaporative cooling system is the feasible non-compressor based cooling systems that can reach the cooling performance required. This two evaporative cooling system has some different in construction, porous material used, airflow scheme and secondary air cooling method used for various applications. This paper would report the cooling performances achieved by those two cooling system in terms of cooling efficiency, cooling capacity, wet bulb effectiveness, dew point effectiveness, and temperature drop. Porous material used in indirect and semi-indirect evaporative cooling would be highlighted in terms of their type, size, thickness and any other feature. The introduction of nanopore skinless bamboo potency as a new porous material for either indirect or semi-indirect evaporative cooling would be described. In the future study of nanopore skinless bamboo, a surface morphology and several hygrothermal test including sorption, water vapor transmission, thermal conductivity test would be applied, before it utilize as a new porous material for direct or semi indirect evaporative cooling.


2014 ◽  
Vol 1070-1072 ◽  
pp. 1679-1683
Author(s):  
Qin Ouyang ◽  
Guang Xiao Kou ◽  
Min Ouyang

According to the climate conditions of Hunan province and the design parameters related to air conditioning, the energy consumption and the related characteristics of the liquid desiccant evaporative cooling system (LDECS) are compared with primary return air conditioning system. The results show that energy consumption of LDECS can be decreased by 11.78% compared to the primary return air system. LDECS has a certain degree of energy saving potential in Hunan province, especially when waste heat is available.


2003 ◽  
Vol 2 (2) ◽  
Author(s):  
J. R. Camargo ◽  
C. D. Ebinuma ◽  
S. Cardoso

Air conditioning systems are responsible for increasing men's work efficiency as well for his comfort, mainly in the warm periods of the year. Currently, the most used system is the mechanical vapor compression system. However, in many cases, evaporative cooling system can be an economical alternative to replace the conventional system, under several conditions, or as a pre-cooler in the conventional systems. It leads to a reduction in the operational cost, comparing with systems using only mechanical refrigeration. Evaporative cooling operates using induced processes of heat and mass transfer, where water and air are the working fluids. It consists in water evaporation, induced by the passage of an air flow, thus decreasing the air temperature. This paper presents the basic principles of the evaporative cooling process for human thermal comfort, the principles of operation for the direct evaporative cooling system and the mathematical development of the equations of thermal exchanges, allowing the determination of the effectiveness of saturation. It also presents some results of experimental tests in a direct evaporative cooler that take place in the Air Conditioning Laboratory at the University of Taubaté Mechanical Engineering Department, and the experimental results are used to determinate the convective heat transfer coefficient and to compare with the mathematical model.


Author(s):  
Amir Abbas Zadpoor ◽  
Ali Asadi Nikooyan

The evaporative inlet cooling systems used for inlet cooling of gas turbines during hot summers do not work well in humid areas. However, desiccant wheels can be used to dehumidify the air before passing it trough the evaporative cooler. Since the desiccant wheels work adiabatically, the resulting air is hotter than the air introduced to the wheel and an evaporative cooling system is used to cool down the dehumidified air. Combined direct and indirect evaporative coolers have been already used to investigate the effects of dehumidification on the effectiveness of the evaporation cooling systems. It is shown that a single desiccant wheel does not offer much higher effectiveness compared to the multiple-stage evaporative systems. In this paper, an improved version of the desiccant inlet cooling system is presented. Additional dehumidification and indirect evaporative cooling stages are added to increase the effectiveness of the inlet cooling. A typical gas turbine cycle along with an industrial gas turbine with actual performance curves are used to simulate the thermal cycle in presence of the different inlet cooling systems. The simulations are carried out for three different climatic conditions. The improved and original desiccant-based systems are compared and it is shown that the added stages substantially improve the effectiveness of the desiccant-based inlet cooling.


Author(s):  
Wendell Concina ◽  
Suresh Sadineni ◽  
Robert Boehm

Evaporative cooling is among the most cost effective methods of air conditioning, but is less efficient in humid climates. An evaporative system coupled with a desiccant wheel can operate effectively in broader climatic conditions. These cooling systems can substitute traditional vapor compression air conditioning systems as they involve environmentally friendly cooling processes with reduced electricity demand (which is commonly generated from fossil fuels) along with no harmful CFC based refrigerant usage. Furthermore, direct utilization of low grade energy sources such as solar thermal energy or flue gas heat can drive the desiccant regeneration process, thus providing economic benefits. This study presents the results of simulations of desiccant cooling system performance for different climate zones of the United States. Solar assisted desiccant air conditioning is particularly useful where there are abundant solar resources with high temperature and humidity levels. Building energy simulations determined cooling energy requirements for the building. Simulation of an evacuated solar hot water collector model provided the heat energy available for regeneration of the desiccant. Solid desiccant of common material such as silica gel used in a rotary wheel is simulated using established validated computer models; this is coupled with evaporative cooling. Transients of the overall system for different cooling loads and solar radiation levels are presented. Finally, feasibility studies of the desiccant cooling systems are presented in comparison with traditional cooling system. Further analysis of the data presents optimization opportunities. Energy savings were achieved in all climatic conditions with decreased effectiveness in more humid conditions.


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