Experimental analysis and development of an in-house CFD condensation hood model

Abstract

An existing condensation hood has been numerically investigated using k-ε turbulence and species transport models. Due to the geometrical complexity of the appliance, two additional mathematical models were introduced with the use of User Defined Functions (UDFs). They were a model of a fan and a model of the internally finned pipes of a heat exchanger. The latter also involved a condensation model of steam implemented by mass and energy source terms. Such an approach allowed us to avoid troublesome two-phase flow simulation and thus significantly reduced the computational effort. Based on the results provided by the numerical model, potential improvements of the heat exchanger were proposed and implemented into a second, modified numerical model. Reduction of the number of the pipes by 25% is the most important change of the developed device. Its negative effect on condensation efficiency was to be compensated by improvements of steam flow in the device. Once the modifications had been evaluated, the prototype of the device was built and tested experimentally. Both the numerical and experimental results agree and show that, the modified condensation hood is comparable to the original construction in terms of condensation efficiency, despite the significant heat transfer surface area reduction.