The hospitals Heating, Ventilation, and Air Conditioning (HVAC) systems consumed large amounts of energy due to the specific requirements that must be met to ensure that environmental conditions were healthy, convenient, and safe. Therefore, to reduce electricity consumption without sacrificing comfort and improving indoor air quality, the utilizing of heat pipe heat exchanger (HPHE) is necessary and highly recommended. An experimental study was conducted to investigate the thermal performance of heat pipe in recovering the heat of an exhaust air from a room simulator. HPHE consisted of several tubular heat pipes with water as a working fluid and staggered by up to six rows. The outer diameter of each heat pipe was 13 mm and length of 700 mm with fins mounted on each heat pipe. A series of experiments was conducted to determine the effect of inlet air temperature. The influence of the number of heat pipe rows and air velocity was also investigated. The experiments showed that the higher inlet air temperature, the more effective the HPHE performance became. The cooling capacity of the system had increased. It was indicated by the decrease of air temperature entering the evaporator by 2.4 °C with the effectiveness of 0.15. This result was achieved when using six rows HPHE, air velocity 1 m/s, and evaporator inlet air temperature 45 °C. When air velocity was doubled to 2 m/s, the system reached the largest amount of heat recovered of 1404.29 kJ/hour. The overall use of energy in HVAC system from the annual prediction of heat recovery for 8 h/day and 365 days/year would decrease significantly 0.6-4.1 GJ/yr.
This study was conduct to identify the effectiveness and heat recovery values of heat pipe heat exchangers (HPHEs) in heating ventilating air conditioning (HVAC) ducting systems. HPHEs are passive modules which provide the energy recovery function in HVAC systems. In this research the HPHE module consist of 42 heat pipe tubes equipped with 120 wavy fins on the evaporator and condenser sections. In this study the HPHE module was tested with a three-row configuration design, and at inlet airflow temperatures of 28, 30, 35, 40, and 45ºC. The velocity of inlet air also varied, at 1, 1.5, and 2 m/s. The results show that in the three-row configuration the inlet temperature decreased by a maximum of 10.3°C. This configuration also has an HPHE effectiveness value of between 47.9 and 54.4%. The highest effectiveness value (54.4%) was obtained at inlet air velocity and temperature of 1 m/s and 45ºC, respectively. The highest HPHE heat recovery value was 5,368 W at 2 m/s inlet air velocity, giving a 51.7% HPHE effectiveness rating. This HPHE system can be considered as saving energy for HVAC systems.
As a family of heat pipes, oscillating heat pipes have many additional unique operating parameters. This paper examined the heat transfer characteristics of an oscillating heat pipe that has an effective length (leff) of 500 mm and uses methanol as the working fluid. The effective length of 500 mm is not typically used in previous experimental setups. This structural dimension of the oscillating heat pipe is widely used as a heat recovery device. The heat pipe was tested with various heat supplies and inclinations. The results show that the inclination makes a substantial contribution to the heat transfer capability for large scale heat pipes. Decreasing the degree of inclination reduces the capability of the heat pipe in handling the heat load. Reducing the inclination also decreases the oscillatory motion, which is an obvious "heat carrier" from the evaporator to the condenser.
Heat generated in an electric motor can increase the operating temperature. The excessive operating temperature w ill reduce the electric motor performance and shorten the service life. An appropriate thermal management system is required to reduce the electric motor operating temperature. The objective of this study is to determine the thermal performance of pulsating heat pipes w hich applied to the electric motor thermal management system. A prototype of electric motor thermal management system w as made from an induction motor w ith a cartridge heater instead of a heatgenerating rotor and stator. Six pieces of pulsating heat pipe w ere mounted using hexagonal heat pipe holder w hich placed inside the electric motor housing. The pulsating heat pipes are made of a copper capillary tube using acetone as w orking fluid w ith a filling ratio of 0.5. The electric pow er input w as varied from 30 W to 150 W. The use of pulsating heat pipes can reduce the electric motor surface temperature by 55.3°C w ith the minimum thermal resistance of 0.151 °C/W.
Thermoelectric cooler is one type of refrigeration system that is environmentally friendly because it does not use refrigerants which have potential damaging the ozone layer. In this study, an experimental performance of thermoelectric refrigerator using fan and without fan is presented. The result shows that the cold side temperature decreases from 25.5 degree C to -5 degree C for 37 watt (with fan) and 25.5 degree C to -7.5 degree C for 37-watt without fan. Using 43-watt power supply, the cold side decreases from 25 degree C to -5 degree C for fan usage, and from 26 degree C to -7.5 degree C in 60 minute and 75 minutes, respectively. Using fan for cold sink inside the cabin will distribute the cabin temperature of cool box evenly and also increase the capability of heat transfer performance of cooler box of thermoelectric. Maximum average COP is 0.103 and achieved by 37-watt power supply with cold sink fan.
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