Abstract: Thermocline storage tanks for solar power systems are disclosed. A thermocline region is provided between hot and cold storage regions of a fluid within the storage tank cavity. One example storage tank includes spaced apart baffles fixed relative to the tank and arranged within the thermocline region to substantially physically separate the cavity into hot and cold storage regions. In another example, a flexible baffle separated the hot and cold storage regions and deflects as the thermocline region shifts to accommodate changing hot and cold volumes. In yet another example, a controller is configured to move a baffle within the thermocline region in response to flow rates from hot and cold pumps, which are used to pump the fluid.

Abstract: The present invention is directed towards a water heater having a combustion chamber and a water tank positioned adjacent to the combustion chamber. The water tank has a flue tube extending through or surrounded by the water tank and has an upstream end positioned to receive combustion gases from the combustion chamber and a downstream end positioned to exhaust the combustion gases. The flue tube also has a wall that extends between the upstream and downstream ends. The wall of the flue tube has an inner surface defining a combustion gas passage and an outer surface positioned to contact water received in said water tank. The walls have convolutions along at least a portion of their length and are configured to reduce laminar flow of the water adjacent the outer surface of flue tube, thereby providing increased heat transfer between the combustion gases in the flue tube and the water in the water tank.