Natural ventilation with heat recovery using heat pipes.

Natural ventilation based on Passive-stacks are currently designed without incorporating heat recovery leading to wasteful heat loss. Heat recovery is not used because the pressure loss caused by conventional heat exchangers is large and could cause the ventilation system to fail. This paper presents laboratory investigation and computer simulation of a low pressure-loss heat recovery device for passive stack systems. It was found that the heat recovery effectiveness decreases with increasing stack velocity and heat recovery effectiveness of over 50% has been obtained in the experiments. It was also demonstrated that acceptable pressure losses can be achieved if the stack mean velocity is kept under approximately 1 m/s.