This research aims to study the parameters have affected the pipe which was studied the heat transfer characteristics of a heat pipe with a mesh wick. The heat pipe made from copper tubes with intemal (ID) as 10 and 12 mm and length of 30 cm which was installed a copper mesh wick inside a tube. Three working fluids are distilled water ethanol and refrigerants-11 (R-11). The filling ratios is 50% with respect to evaporator volume. The operating temperature at the evaporator section is: 50 70 and 90 oC. The condenser section has cooked by water with a flow rate of 0.5 L/min. Then all of the experimental data were compared with the heat pipe without copper mesh wick. It was found that heat pipe at ID 12 mm yielded a better heat transfer rate when compared with heat pipe without a mesh wick. The heat pipe produced a heat transfer rate value of 7.3 W and heat pipe efficiency of 58.5 at evaporator section’s temperature of 90oC. In addition the mesh wicks will help transfer the working fluid in the condenser section return to the evaporator section. The condensed liquid had spread around the walls of the heat pipe. The working fluid was condensed to the evaporator section then affected to a higher heat transfer rate.

This research is to study in heat transfer of hot water tank from an air conditioner which is a cylinder type and has a hot water pipe around the tank. It is used for finding a position and a pattern of distribution of the hot water pipe around the tank in the highest heat transfer condition. The study uses the cylinder of hot water tank filled 45 liters of 25 oC water. An experiment separates in 3 positions of pipe wrapping which are the bottom the center and the top of the tank. Then 80 oC of hot water run thought the hot water pipe which is wrapped around the tank for 120 minutes. The result of the experiment shows that tubing position that causes the highest heat transfer is at the bottom of tank. Pipe wrapping at the bottom of the tank has the heat transfer higher than the top of the tank at 30%. Furthermore this experiment studies in spacing of hot water pipe. There are 3 types for testing which are spacing hot water pipe as one time two times and three times of diameter of pipe. The result illustrates that spacing the hot water pipe can significantly increase the heat transfer. The heat transfer of spacing the hot water pipe in three times of diameter of pipe is higher 5.8 % than spacing in one times. In addition this research is to study in the effect of turbulent flow on the heat transfer by installing agitator in order to stir water in the tank. The result is that water stirring in the tank for increasing the heat transfer is not effective for investment because the energy using for stirring is higher than the enhanced heat transfer

This research was aimed to study melting behavior of paraffin wax and to evaluate the natural heat convection coefficient of solid cylinder paraffin wax. Two grades of solid paraffin wax; white commercial grade and yellow market grade were studied. Three sizes of flat test tube in diameter 1.5 2.0 and 2.5 centimeters were used. Three different amounts of paraffin indicated from samples’ heights of 5 7 and 10 centimeters were set. The results found the average melting point of both grade paraffin ranged from 44-77 oC. Based on the numerical analysis heat behavior of solid cylinder paraffin at the initial temperature of 50 oC to room temperature of about 30 oC found that natural convection coefficients was ranged from 3 to 9 W/m 2oC. Melting point temperature was found mass independent property while natural convection coefficient declined as the sample’s diameter size inclined

The performance investigations of subcritical ORC supercritical ORC and trilateral Rankine cycle (TLC) power plants with the heat source temperatures of 210-250°C were conducted and compared in this study. Several working fluids were evaluated. A MATLAB code was developed and used in this study. The thermodynamic properties of the working fluids were calculated by using NIST REFPROP program. The justification of the code was validated with a result taken from the literature. The optimal operating conditions were searched using the golden-section technique. The maximum net output power of 141.72 kW was obtained when using the supercritical ORC plant with R141b as its working fluid and the heat source temperature was at 250°C. The corresponding cycle efficiency was 16.25%. When using the subcritical plant at the same heat source temperature the maximum net output power of 133.40 kW and cycle efficiency of 15.70% are obtained when pentane is used as the working fluid. Furthermore the net output power of 133.82 kW and cycle efficiency of 14.90% are obtained when using R141b as the working fluid in the TLC power plant. According to the off-design simulations an appropriate adjustment of the working fluid flow rate can mitigate the variation of the net output power.

The solar chimney power plant (SCPP) has been proposed as a promising alternative power plant. According to the literature the chimney for commercial-scale SCPPs should be about 1 km high. The construction of these tall chimneys is very challenging and the construction cost is enormous. The sloped solar chimney power plant (SSCPP) is a variation of the SCPP. One of the SSCPP’s prominent feature is that its collector is sloped and then its chimney can be shorter than that of the SCPP. This leads to a lower investment cost of SSCPPs compared with that of SCPPs. Also previous studies show that the industrial waste heat potential of Thailand is considerable and should be investigated. As a result this study developed a mathematical model for designing a sloped solar chimney power plant powered by industrial waste heat (SSCPP-WH). The model was justified by validation using experimental data. Then several SSCPPs with different geometrical dimensions were simulated to determine a proper dimension that has the lowest levelized cost of electricity (LCOE). It was found that the LCOE is about 0.14 USD/kWh the payback period is about 11 years system efficiency of 1.3% and collector efficiency of 36%. for an SSCPP-WH with a collector area of 49000 m2 chimney height of 45m flow area ratio between solar collector inlet and solar collector outlet (AR12) of 14 and waste heat of 10 MW. It was also found that the payback period of SSCPP with no supplied waste heat is lower than that of some SSCPP-WHs. To make sure that the payback period for the SSCPP-WH is faster than that of SSCPP with no waste heat a ratio of the supplied waste heat to the absorbed solar energy of the SSCPP-WH must be greater than 0.34.