RP-824 -- Characterization of Frost Growth and Heat Transfer at Low Temperatures PDF

ASHRAE Research Project 824 "Characterization of Frost Growth and Heat Transfer at Low Temperatures" had as its objectives:

(1) measurement of the characteristics of frost as it grows on a flat plate at low temperatures. These data are to include heat flux, frost height, and frost mass concentration as a function of time and position for a range of operating conditions with supply air temperatures as low as -25°C and high air relative humidities and plate temperatures as low as -40°C,

(2) measurement of the characteristics of frost as it grows on heat exchanger fins at low temperatures. These data are to include heat rate, frost height distribution and frost mass accumulation as a function of time and position for a range of operating conditions with supply air temperatures as low as -25°C and high air relative humidities and fin. temperatures as low as -40°C,

(3) inclusion of an uncertainty analysis and some attempt to present the measured data in a form suitable for the designers of refrigeration heat exchangers, and

(4) inclusion of a research report and research papers.

This report contains a comprehensive review of the literature on frost growth, especially as it pertains to heat exchangers. New test loop facilities were developed to investigate frost growth on flat plates and heat exchanger fins. New instrumentation was designed, calibrated and demonstrated for frost growth on heat exchanger fins. A major development was the frost height measurement system for heat exchanger fins using an automated laser scanning system where both transmitted and scattered light was monitored and analyzed to predict frost height. Data from this laser scanning system allowed the presentation of frost height at each position on a two-dimensional fin.