Abstract
In order to improve thermal efficiency of a gas water heater, an additional heat exchanger is required for latent heat recovery from the exhaust gas. In this study, two types of smooth-tube bank heat exchanger with a staggered and inline tube arrangement were installed to a commercial hot water heater with the output of 34.8kW, and the performance was evaluated under a normal using condition. The experimental results were compared with numerical results by a model based on the analogy between heat and mass transfer. The tested heat exchanger satisfied the required performance, which is a thermal efficiency of 89% based on HHV. Experimental results of heat transfer rate showed higher values than the numerical results, though those of condensing rate showed lower values.
