Use of waste water heat for supply water heating by use of heat pipe diodes

A hot supply water storage tank, which is heated by waste water heat, has been developed by Dornier System GmbH. Copper heat pipes using water as carrier fluid have been developed for this purpose, which are capable to transfer sufficient heat even at temperatures as low as 10 C. Measurements indicate that up to 90% of the usable waste water heat may be recovered depending on the waste water flow rate and on the complexity of the system. Stratification within the tank allows that more than 75% of the stored energy may be drawn without a significant drop in supply water temperature.