Experimental studies on Residential Split AC Water Heater (RSACWH) by replacing refrigerant R-22 with HCR-22 (hydrocarbon refrigerants) as a drop-in substitute has been carried out. The dummy condenser (trombone type coil) as heat recovery system was used for heating water and installed in the water tank with 50 L capacity. The use of HCR-22 save electrical energy due to decrease in compressor power about 16.31% - 21.64% of the R-22, because HCR-22 refrigerant mass charge in the refrigeration system 40% less than the charge of R-22. The cooling capacity and heat rejection capacity is relatively the same for R-22 and HCR-22. The COPR increases around 11.89% - 18.69% and COPR + HP also increases around 4.26%-11.41% for HCR-22 compared to R-22. The room temperature with HCR-22 is relatively the same compared to R-22, while the hot water temperature using HCR-22 and R-22 are about 46.58˚C-48.81˚C and 59.50˚C-63.40˚C respectively. The use of the HCR-22 provides electrical energy savings for compressor power and better performance (COP) at similar room temperature compared to R-22.
Thermal Engineering Laboratory, Departement of Mechanical Engineering, Universitas Riau, Pekanbaru, 28293, Indonesia
Departement of Mechanical Engineering, Universitas Bengkulu, Bengkulu, Indonesia
Mechanical transfer switch has been utilized for decades to mitigate outage due to failure in electricity supply. In this paper, we introduce novel method of transfer switch transition mechanism. Traditional transfer switch uses 2 contactors in interlocking mechanism, in that when main contacts of first contactor is at close position, the second contactor is locked at open position and so with conditions reversed. The proposed transfer switch uses variable reluctance stepping motor to drive contacts transition mechanism. The developed stepping motor has 6 poles at the stator and 4 teeth at the rotor. With this construction, the stepping motor will have 30-degree of step angle. The rotor of the stepping motor then directly drives the cam operated switch which has 2 groups of contacts where the first group connects the load to the grid network and the second group connects the load to the generating set. If rotor rotates 30-degree counter clockwise from the neutral position, the load will be connected to the grid network. If rotor rotates 30-degree clockwise from neutral position, the load will be connected to the generating set. By operating the control switches in stepping motor control circuitry correctly, the proposed transfer switch is capable to make transition between 2 sources of electricity safely. Moreover a grip handle mounted onto the rotor shaft allows manual operation of transition mechanism.
Department of Electrical Engineering, Universitas Riau, Pekanbaru, 28293, Indonesia
Building-integrated urban wind turbines are promising low-cost renewable energy devices. However,the take-up of urban wind turbines in high density suburban environments is still very interesting to investigate by issues such as: a) low wind speeds; b) high turbulence intensity; and c) the perception of potentially highlevels of aerodynamic noise generated by the turbines. This paper presents a numericalstudy was performed to C building Faculty of Engineering University of Riau using type of RANS turbulence k-e models in the open source code OpenFOAM, and the results are compared with published in-situ measurements and published wind tunnel tests.Based on the computational results, site for wind turbine installation above these roofs has been assessed. It has been found that turbulence intensity and wind direction for mounting wind turbine site is 1.8H in the corner location above roof C building.
Department of Mechanical Engineering, Universitas Riau, Pekanbaru, 28293, Indonesia