Investigation of Immersed Coil Heat Exchangers in regard to Heat Transfer and Storage Stratification
Current implementation of Immersed Coil Heat Exchangers (IHX) into Solar Domestic Hot Water (SDHW) systems use simple guidelines for dimensioning their surface area based on an intended solar collector area - or range thereof. The literature from whence these guidelines come (1970s and 80s) are based on experiments with different types of IHX (copper, flange-retrofitted) to those used today and are evaluated solely on the performance of heat transfer, thus a re-evaluation of these guidelines is considered necessary. The investigations presented attempt to combine an evaluation of the heat transfer performance and stratification together based on measurements from three IHX samples with varying material and geometrical arrangement. Preliminary analysis suggests a correlation between high convective heat transfer coefficients and low stratification efficiencies.