SBIR-STTR Award

Heat exchanger design optimization of size, weight and cost usually requires that at least one, and sometimes both surfaces of the wall separating the two heat exchange fluids, be extended in area. This objective is easily accomplished by raising fins on the outside surfaces of tubes. When it is necessary to increase (or extend) the inside surface of a tube, without unacceptable interference with the fluid flow, the problem is compounded. The commercially available tubes with extended inner surfaces are of limited utility and designers usually opt to use a large number of small, smooth-bore tubes. These designs are costly and easily damaged. This research proposes to develop the design of a new heat transfer matrix which will have extended surfaces without the problems associated with the currently available materials. The new matrix is particularly well suited for encapsulation in tubes, but is also useful in other void volumes

The function of a heat exchanger is dependent upon the area of exposure to the fluids in process. Fins are commonly used to increase external surface areas. To extend the inner surface of a tube or vessel is more difficult and there is currently no cost effective method to do so. This research is to develop the use of a matrix composed of small, hollow, metal cylinders, brazed together at their contact points as a heat transfer matrix. Encapsulating this matrix in tubes extends the tube inner area. The matrix has a high area/ weight ratio and is rigid and light weight, and is vibration and shock resistant. A priority application is one for use within U.S. Army combat tanks