Abstract :
This paper evaluates the performance of narrow-gap vertical mantle heat exchangers with a two-pass arrangement for use in pumpedcirculation
solar water heaters. Both measured mantle side and tank side heat transfer correlations have been developed and implemented
in a TRNSYS model of a complete solar water heater incorporating this type of heat exchanger. Predictions of the annual solar
contribution for mantle–tank systems are compared to direct-coupled systems. The direct-coupled systems are found to provide slightly
higher annual energy saving than mantle–tank systems for standard domestic hot water demand in Australia. However, the reduction in
performance is outweighed by the benefit of freeze protection provided by incorporating a collector loop heat exchanger in the system.
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