Abstract: This invention is a phase change heat exchange unit which is comprised of upper and lower skeletal support frames having a container for a phase change material disposed therebetween. Each of the frames has a pair of support grids which provide support for the phase change material container and provide a passage for the flow of a heat transfer fluid therethrough so that it can come into direct contact with the container.

Abstract: An energy storage medium that can be raised to a high energy state which is comprised of a gel of polyethylene oxide, water, and a salt which causes gelation of polyethylene oxide and water at or below about 90.degree. C., and a method for storing energy with the medium.

Abstract: This invention relates to a microwave leakage detector of the kind suitable for use in a domestic environment for testing leakage from appliances such as microwave ovens by moving the detector along joins or seals of the appliance. The circuitry of the detector is generally known per se. In order to facilitate testing of the detector in the domestic environment the circuitry and associated dipoles are fully encased in a solid block of material in a container having a head portion for accommodating the circuitry and a handle for convenience in use. The container is a clear plastics material enabling a visual warning device associated with said circuitry to be viewed externally and the container has a specific gravity greater than that of water whereby said device is adapted to sink when placed in water. Thus testing of the detector may be readily effected by placing it in a container of water within an oven such that the warning device may be viewed externally of the oven.