Solar Thermal Collector Efficiency Equation

Solar thermal collectors are classified by the united states energy information administration as low medium or high temperature collectors.

Solar thermal collector efficiency equation.

Simply stated collector efficiency is. It changes as the operational conditions change. The solar collector can be divided in two subsystems. The solar thermal energy can be used in solar water heating systems solar pool heaters and solar space heating systems.

A value of 60 80 is common for most thermal solar collectors but this value needs to be taken with a grain of salt with the surface area it is based on considered. Thus the thermal efficiency of the solar collector is η coll q r i t 0 a a. The thermal efficiency of a solar heat collector is not static. P ti ta i p inlet fluid parameter.

They gather the sun s energy transform its radiation into heat then transfer that heat to a fluid usually water or air. A solar thermal collector collects heat by absorbing sunlight the term solar collector commonly refers to a device for solar hot water heating but may refer to large power generating installations such as solar parabolic troughs and solar towers or non water heating devices such as solar air heaters. The solar collector efficiency represents the ratio between the heat absorbed by the solar receiver q r and the incident solar radiation i t0 normal on the collector s aperture of area a a. Low temperature collectors are generally unglazed and used to.

Obviously the higher the useful energy output from a particular design the higher the expected efficiency. Useful energy absorbed solar energy thermal losses. Solar collectors solar collectors are the key component of active solar heating systems. Solar thermal collectors are either non concentrating or concentrating.

Ti inlet fluid temperature to the collector ºf ta ambient air temperature surrounding the collector ºf i solar radiation intensity striking the collector btu hr ft2. The inlet temperature of 40 c with a flow rate of 3 liters minute gives a range of efficiency values of glazed flat plate solar collector of 32 64 unglazed flat plate solar collector is 26 53. Solar collector performance variables can be used to promote the performance of a solar collector in particular the peak efficiency value is used. The thermal efficiency of a collector is calculated by using the formula bellow.

Thermal efficiency of the collector is an important parameter to consider in this kind of analysis as it creates the basis for comparison of different materials and modifications of.