In this study, thermal treatments have been investigated for different channel angles and mass flow rates of a compact heat exchanger have been manufactured by direct metal laser sintering technique instead of a sealed and brazed one used in many areas. Boundary conditions of available heat exchanger experimental test have been used in laboratory. In this study, we have designed for compact heat exchanger of 30• , 45• and 60• channel angle and used three different mass flow rates (0.2, 0.3, and 0.43 kg/s). Heat transfers occurring between heat channels and walls of heat exchangers for different channel angles and efficiency of heat exchangers have been calculated. As a result of the analysis, it has been determined that in order for maximum of heat transfer of a compact heat exchanger, following working conditions ought to be fulfilled: channel angle 30• , hot water input temperature 60• C, cold water input temperature 15• C, and mass flow rate 0.43 kg/s.

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In this study, instead of gasketed or brazed plate heat exchangers, which are used in various fields of application, a direct metal sintering method is used to design a heat exchanger with its original geometry and with different geometries. Studies of heat exchangers found in published literature were reviewed, and the thermal behaviors of the proposed unique designs were examined. Usually heat exchangers using this design do not use channel spacing angles of 30-45-60-75• for the plate ducts. The thermal behaviors of the fluid-circulating systems were analyzed using ANSYS FLUENT software, and they used the boundary conditions found in the literature for this design. Heat transfer between the heat exchanger channels and channel walls was calculated. The analyses results show that an increase in the amount of heat transfer surface area and also an increase in surface roughness increased the amount of positive heat transfer.

Pulverized coal combustion is extensively used in utility boilers, industrial boilers, furnaces, kilns, and other energy conversion appliances. The effective utilization of pulverized coal is the main problem in study of combustion processes, particularly in burning low-grade coal. It is well known that the emission of nitrogen oxides (NOx) during coal combustion is a main environmental problem. In this study, three different pulverised coal burner geometries for a pulverised coal fired boiler have been studied by numerical analysis. GLI-Tunçbilek coal was used as fuel. Threedimensional numerical analysis was carried out using Ansys Fluent code. Realizable K-ε turbulence method, single rate devolatilization method, multiple char combustion method and second-order upwind discretization method were used during calculations. Coal particle diameter and coal mass flow rate were assumed to be 70 µm and 378 kg/h respectively.