This standard applies to latent heat thermal energy storage devices in which a transfer fluid enters the device through a single inlet and leaves the device through a single outlet. This standard is not applicable to those configurations in which there is simultaneous flow into the storage device through more than one inlet or simultaneous flow out of the storage device through more than one outlet. The transfer fluid can be either a liquid or a noncondensing gas. This standard does not include factors relating to cost@ life@ or reliability. It anticipates a variety of energy sources but does not consider the interfacing requirements of any specific heating or cooling system. In particular@ the five cycles prior to testing specified in Section 5.1 are not intended as a measure of phase-change material degradation. The test procedure and equipment outlined in this standard are most easily adaptable to devices used to store thermal energy on the order of 107 Btu (1010 J) or less. This standard permits testing of a storage device containing a source of internal heating@ such as a stirring pump or an electric immersion heater@ provided that less than 10% of the charge capacity in a test is supplied by the internal heating. If such a source of internal heating is used@ the internal heat input must be measured and Equations 2 and 5 must be appropriately modified. PURPOSE The purpose of this standard is to provide a standard procedure for determining the thermal performance of latent heat thermal energy storage devices used in heating@ airconditioning@ and service hot water systems.