Temperature control

For the case of a PCM based heat storage operating at the phase change temperature, the temperature is determined by the actual PCM. This can be a suitable concept for frying and baking.

For the case of heat storage being charged with a heat transfer fluid,we would like the storage to provide energy back to the cooker at the same temperature as the charging, at any time. This is to avoid having to wait for the storage to be fully charged before making use of the energy. A temperature control is then needed such that the storage is charged at a desired temperature.The system can be suitable for cooking, as the heat transfer can be regulated by the flow rate.

We are looking for solutions where an oil is heated and at a set temperature, the hot oil delivered to a heat storage. The heat storage can be a separate hot oil tank, or a vertical container with thermal stratification (hot oil on the top).

We need solutions for the valve and the actuator which drives the valve at a set temperature.  

            

   

We apply similar requirements for the the temperature control device as for the heat storage concept: it should be simple, robust and possible to construct and maintain locally. We thus try to avoid sensors, powered actuators and high precision mechanical components.
See further on the experiences we have on valves  and actuators .

Expansion based flow control In one of the concepts we have tested, the valve is not present, as the flow is based on overflow across a barrier. A natural circulation system is made by connecting a storage and a heater pipe with a lower and an upper pipe. The circulation can be hindered by a barrier at the upper part. As the oil expands during heating, overflow across the barrier starts at a given temperature (depending on the barrier height) and circulation to the storage is initiated. The position of the barrier also serves to control the flow rate when cooking from the storage energy.