Calorimeters, Solar collectors


The reference heat source (RHS) is an electrical calorimeter used with solar collector test facilities. It can be used to calibrate the test facility or to measure the thermal performance of a collector. The RHS described here was designed to be accurate enough to be used as a standard for verification of test facility calibrations. The core of the unit consists of resistance heaters, platinum resistance thermometers, a thermopile, and flow mixers. This core is surrounded by a thermally driven copper shield to control heat loss. The electrical power input to the core is measured with an electronic power transducer. The output of this transducer as well as the temperature sensors is indicated on digital panel meters. All measurements are made independent of the test facility's data acquisition system. The entire unit is mounted on a 0.5 x 1.5 m cart for portability.

In operation, liquid from the test facility is circulated through the RHS core. The liquid is heated by passing over the resistance heaters. If the test facility's calibrations are under investigation, the RHS input power and temperatures are compared with those recorded by the test facility. If a collector is under test, the RHS is placed in series with the collector. The power input to the RHS core heaters is adjusted to give a temperature rise through the RHS equal to some fraction (usually one-half to one) of the temperature rise across the collector. Since the same mass flow passes through both the RHS and the collector, the energy gain in the collector is simply the RHS input power multiplied by the ratio of the temperature rises.

This RHS was designed for use at temperatures from 0°C to 100°C and liquid flow rates from one to forty liters per minute. The results presented here were obtained using typical flat plate solar collectors. The operational experience obtained in an active test facility is discussed with regard to the achieved accuracy, practical operation, and recommendations for further applications.


If this is your thesis or dissertation, and want to learn how to access it or for more information about readership statistics, contact us at

Graduation Date



Eno, Burton E.


Master of Science (M.S.)


College of Engineering

Degree Program





65 p.




Public Domain

Length of Campus-only Access


Access Status

Masters Thesis (Open Access)



Accessibility Status

Searchable text

Included in

Engineering Commons