Analytic model of a passive vapor transport heating system

Abstract After reviewing passive systems for downward transprot of heat, this article presents an approximate mathematical model for one particular system in which refrigerant that is evaporated in a solar collector transports heat to a condenser located at some arbitrary elevation below the collector. The vapor pressure lifts the liquid from the condenser to an accumulator above the collector, from which it periodically flows into the collector. It is shown that the maximum energy delivery to the condenser can occur when the accumulator loses a specified amount of energy to the environment. Use of one of the ordinary refrigerants as the working fluid should be appropriate for passive space- or water-heating systems in which the collector can be several meters above the condenser.