Heat source transfer functions and their application to low temperature radiant heating systems.

摘要

Radiant heating systems have been identified by segments of the HVAC industry as technology which can potentially reduce the energy consumption of buildings. As a result of higher mean radiant temperatures within radiantly heating structures, it has been hypothesized that these systems can provide an equally comfortable thermal environment at lower thermostatic temperatures than conventional forced air systems. Previously, there has been no fundamentally sound way to evaluate this hypothesis. Thus, the main goal of this research was to develop the fundamental technology that correctly accounts for the transient heat conduction inherent in the low temperature systems, fully models the complex interactions with the rest of the building, and evaluates the resulting thermal environment created by the system.;Time series analysis has been established by previous studies as an accurate and efficient method of calculating transient one dimensional heat conduction through standard building elements. The heat source transfer functions (QTFs) derived in this work are an extension of time series analysis to include the effects of an embedded source or sink of a radiant heating or cooling system on transient conduction. Heat source transfer functions were obtained through both the more traditional Laplace transform method and the newer state space method which could be adapted to two dimensional solutions. Through comparison to an analytical solution and experimental data, the concept of heat source transfer functions was validated.;The incorporation of a low temperature radiant system model into the Integrated Building Loads Analysis and System Thermodynamics (IBLAST) program combines the advantages of QTFs with a proven energy balance based simulation that thoroughly describes building heat transfer processes. The new model provides researcher and designer with an engineering tool that can compare radiant and forced air systems on the basis of equivalent thermal environments as defined by accepted thermal comfort models.