The apparatus consists of a collector mounted on a suitable stand, storage tank, pump and insulated pipes. Copper-constantan (Type T) thermocouples are used for the measurements of the inlet, outlet and ambient temperatures. A turbine flowmeter
and a SP1110 pyranometer are used for measuring of the flowrate and solar radiation respectively. The data from the seven thermocouples, the pyranometer and flow meter are been recorded by a commercial, mains powered datalogger (using Matlab, via National Instruments datalogger).

The ISO 9806-1, ASHRAE Standard 93-86 and SRCC document RM-1 provide the standard test methods for flat-plate solar collectors. The general test procedure is to operate the collector in a test facility under nearly steady conditions and measure the data that are needed for analysis. Although details differ, the essential features of all of the procedures can be summarized as below:

1. Solar radiation is measured by a pyranometer in the plane of the collector.

2. Flow rate of working fluid, inlet and outlet fluid temperatures, ambient temperature, and wind speed) are measured.

3. Tests are made over a range of inlet temperatures.

4. The inlet pressure and pressure drop in the collector are measured.

Information available from the test is data on the thermal input, data on the thermal output, and data on the ambient conditions. These data characterize a collector by parameters, FR (та), and FRUL that indicate absorption of solar energy and energy loss from the collector. Instantaneous efficiencies can be determined from:

Пі = Qu/AcGr = mCp (To — Ti )

Ap Gr (5.1)

Where ro is the exit temperature of the working fluid. With the test data over a range of inlet temperatures, the instantaneous efficiency can be plotted as a function of (ri-ra)IGr.

The second important aspect of collector testing is the determination of effects of incident angle of the solar radiation. The standard test methods include experimental estimation of this effect and require a clear test day so that the experimental value of (та) is essentially the same as (та )b. ASHRAE Standard 93-86, recommends that experimental determination of Kt a be done with the incidence angles of beam radiation of 0, 30, 45, 60o. For flat-plate solar collector Souka and Safwat have suggested an expression for angular dependence of KTa as

KTa = 1 + bo( Cos &1- 1) (5.2)

3 CONCLUSION

A mathematical model of the honeycombed collector has been developed. It estimates the net solar energy collected per unit area of the collector. This system consists of a flat plate collector, with a triple walled extruded polycarbonate substituting for the glass cover and absorber plate. The utilisation of the polycarbonate in the solar collector has the advantage of reducing the weight by more than half in comparison with a traditional collector using essentially metals with similar performances [7].

This program was designed to study the properties of a polycarbonate solar collector. The model also facilitates changes to the collector physical properties such as dimensions of the channels, ambient temperature, flowrate, selective and non­selective absorbers, material thermal properties, collector and system design optimisation.

The results from the program will allow a full parametric study of different collector design criteria, with this polycarbonate structure. The results will be compared to a standard flat plate collector design, to see if this polycarbonate flat plate collector is a more effective design. The simulation results are being validated with current experimental testing. ISO 9806-2 standards are being used to validate the results, for the parametric study in the lab, under steady state conditions. The final optimum design will then be tested outdoors using the quasi-dynamic conditions set out by the European Standard EN 12975-2. Weather data, obtained from the weather station set up at CIT, will be used as the input for the weather conditions for out door testing. Following the testing, long-term prediction of this type of collector performance will be looked into.