c. aghanajafi

In underground U-tube heat exchangers (boreholes) it is important to predict its heating performance to design and select the proper parameters such as length, diameter, material etc. to have an optimized borehole from the point of view of heat capacity and economical aspects. For this reason, having trusty equations is vital to foresee borehole heating performance and applying it in design issues. In this study a single vertical U-tube borehole with constant wall temperature is considered and analytical equations for temperature distribution in the surrounding ground around the borehole is evaluated based on one and two dimensional heat conduction respectively. The analytical equation is compared to experimental data for a borehole with 50 m depth in which warm water of 40 C is pumped into it a time period of 120 hours and the heat transfer rate per unit length is recorded. The comparison between analytical expression and experimental data shows a good agreement between them. Also the borehole entropy generation number is studied and the optimized parameters are evaluated to minimize it. It is concluded that for the considered borehole, entropy generation number is decreased by increasing its length and by decreasing the borehole radius and pipe outer radius.

This paper examines the total annual cost from economic view heat exchangers based on ant colony optimization algorithm and compared the using optimization algorithm in the design of economic optimization of shell and tube heat exchangers. A shell and tube heat exchanger optimization design approach is expanded based on the total annual cost measured that divided to area of surface and power consumption. The optimization and minimization of the total annual cost is considered as the objective function. There are three parameters as decision variables in optimization algorithm such as tube outer diameter, shell diameter and central baffle spacing. Two cases studies considered to demonstrate the accuracy of algorithms Results have been compared with the findings of previous studies. The total annual cost is reduced about 10% and 40% for case 1 and 2 using ant colony optimization algorithm, respectively.

Design of radiation paint cure ovens in automotive industries is an important yet difficult task which has not been discussed adequately in the open literature. This is particularly true when complex body frames are considered. In this paper a numerical dynamic optimization algorithm is proposed which provides the optimum temperatures of a fixed number of radiation panels installed on the ceiling of an automotive paint cure oven. Using a paint cure window criterion to define the admissible design space and the objective function, a nearly uniform and satisfactory paint curing condition is obtained at the optimum design point. To describe the method in a simple, clear and computationally affordable context, a two-dimensional section of an oven and the automobile body is considered. It is shown that even the classical steepest descent optimization method converges fast enough in this particular application. The proposed method is also applicable in three-dimensional problems. J. Color Sci. Tech. 3(2009), 107-119.© Institute for Color Science and Technology.