Performance Evaluation of Wire Cloth Micro Heat Exchangers

Abstract

The purpose of this study is to validate a thermal-hydraulic simulation model for a new type of heat exchanger for mass, volume, and coolant/refrigerant charge reduction. The new heat exchanger consists of tubes with diameters in the range of 1 m m and wires in the range of 100 m , woven together to form a 200 × 200 × 80 m m 3 wire cloth heat exchanger. Performance of the heat exchanger has been experimentally evaluated using water as inner and air as outer heat transfer medium. A computational thermal and fluid dynamic model has been implemented in OpenFOAM®. The model allows variation of geometry and operating conditions. The validation of the model is based on one single geometry with an opaque fabric and air-side velocities between 1 and 7 m / s . The simulated and measured pressure drops are found to be in good agreement with a relative difference of less than 16%. For the investigated cases, the effective heat transfer coefficients are in very good agreement (less than 5%) when adapting the contact resistance between tubes and wires. The numerical model describes the fluid flow and heat transfer of the tested heat exchanger with adequate precision and can be used for future wire cloth heat exchanger dimensioning for a variety of applications.

Numerical and Experimental Investigation of Wire Cloth Heat Exchanger for Latent Heat Storages

“…In the experiment, there might be a resistance, which reduces the thermal power. Further, there could be a thermal resistance between the tubes and wires, like investigated in [30]. For the simulation, a perfect contact is assumed.…”

“…The small tube diameter allows to withstand high pressure, which is needed for example for high temperature storages for industrial processes including evaporation processes. Furthermore, the weaving process allows the manufacturing of large-scale heat exchanger elements, and also curved shapes are possible as the wire cloth is flexible [30]. Due to the high heat transfer area and low volume fraction of the wire, the heat exchanger can be used especially for applications with high power and storage density requirements.…”

“…The structures are explained in detail in [29]. Up to now, these types of wire cloth heat exchanger are only investigated as liquid-gas heat exchanger [30,31]. The wire cloth meets the requirements of a high thermal conductivity as well as a large heat transfer surface.…”

Heat Transfer through Wire Cloth Micro Heat Exchanger

“…The numerically determined correlations, as well as the promising application of coated heat exchangers for chemical reaction engineering, must be experimentally evaluated and validated in future work. The first experimental results for wire cloth heat exchangers were published by Fugmann et al [3,11].…”

“…We refer to an improved and improved and patented concept that increases the thermal contact, as presented in [8]. Experimental and numerical investigations of these systems were conducted by Martens and Fugmann et al [9][10][11], with an extension to different wire-on-tube structures by the latter authors. The improvements resulted in increased heat transfer coefficients which are in the upper range of comparable compact heat exchangers.…”