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Plate spacing is one of variable that influences plate heat exchanger (PHE) design as a condenser in Organic Rankine Cycle (ORC) system. The rises of plate spacing have effects to channel cross sectional area, channel velocity, equivalent diameter, and Reynold number at hot and cold fluid sides in PHE. Those parameters affect the total heat transfer area and total pressure drop that influence the PHE condenser performance. This paper investigated the detail effect of the plate spacing increments in the final total heat transfer area and total pressure drop design result. The plate spacing in design calculation method is varied and the other independent variables are assumed to be constant. The design was conducted by calculating condenser capacity at both sides and both zones, estimating overall heat transfer coefficient, and calculating heat transfer area and plate film coefficient. Analysis continued by calculating overall heat transfer coefficient that has small percent of error with the estimated overall heat transfer coefficient, calculating pressure drop, total plate number and total heat transfer area. The result of calculation shows that the rises of plate spacing increase the total heat transfer area and decrease the cold and hot fluid total pressure drop. The rises of plate spacing increase channel cross sectional area and equivalent diameter, and decrease channel velocity and Reynold number at zone 1 (without phase change) and zone 2 (with phase change). Therefore, the increment of heat transfer areas is unpreferable and the decrement of pressure drops is preferable.

This paper presents the electricity power potency estimation from hot spring in Indonesia with temperature 70-80°C using Organic Rankine Cycle (ORC). ORC is a system that able to generate electricity with a low heat source temperature, making it suitable to be used to generate electricity with hot spring as heat source. Organic fluid is used as working fluid in the system. Temperature and volume flow rate of the hot spring is used as the data. The regions to be analyzed are area that has hot springs temperature between 70-80°C. The cold water temperature to be used in the analysis was assumed 5°C lower than ambient temperature. R227ea was chosen as working fluid in the system. The analysis begins by calculating hot spring mass flow rate to determine heat input. Analysis was continued by calculating heat output. End of the analysis are determiningturbine power and thermal efficiency. Results of the analysis indicate that Lompio -1 is the area that has the highest electricity potential compared to other areas with 130.13 kW turbine power and thermal efficiency of 5.71%. Areas that have the lowest electricity potential is Kambahan with 1.14 kW turbine power and 5.63% thermal efficiency.

A photovoltaic (PV) system integrated with a bi-fluid cooling mechanism, which is known as photovoltaic thermal (PVT) system, was investigated. The electrical characteristics of flexible solar panel were evaluated for PV and PV with bi-fluid (air and water) cooling system. The integration of monocrystalline flexible solar panel into both systems was tested under a fixed solar radiation of 800 W/m2. A total of 0.04–0.10 kg/s of air flow was utilised in PV with cooling system with a fixed water mass flow rate of 0.025 kg/s. The efficiencies of flexible panel for PV and PV with cooling system were explored. For PV with bi-fluid flow, the highest obtained efficiency of module was 15.95% when 0.08 kg/s of air and 0.025 kg/s of water were allowed to flow through the cooling system. Compared with PV without cooling mechanism, the highest efficiency of module was 13.35% under same solar radiation. Current–voltage and power graphs were also plotted to present the electrical characteristics (current, voltage and power) generated by both systems.