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Question 1 An existing sport centre heating system will be refurbished to a high standard. Listed below two options are being considered by the management team. However, in order to take final decision they seek further information. From you analysis below suggest the appropriate option with reasons. (10%) Option 1: Solar water-heating system. The glazed flat plate solar water collectors are proposed with total gross area of 500m² and total absorber area as 200m2 to pre-heat the water heating system. The performance of the collectors given on a solar collector efficiency chart n against a heat loss parameter 4) with the following specifications: intercept = 0.8 and slope = 5 (downwards). -ta (i) Sketch and label the graph of against collector efficiency n and determine the solar collector efficiency, if the water inlet temperature is 32°C, the ambient temperature is 20°C and the solar irradiance is 800W/m2 (20%) (ü) Using the collector efficiency derived above, determine water inlet temperature, heat delivered by the collectors and mass flow rate of the collectors if the solar irradiance is 800 W/m2, the ambient temperature is 10°C and water outlet temperature is 75°C. Take cp (H2O) = 4200J/kg-K. (30%) Option 2: Solar air-heating system. The solar air-heating collectors which form the heating system are to be arranged so that they draw in outdoor air. The resulting pre- heated air then passes from the solar collectors to ducts feeding the conventional warm-air heating system supply in the sports centre building. There is no-recirculation of air to the solar collectors. The data required is listed below: Total gross area of collectors Total aperture area of collectors Solar irradiance on collector Overall collector heat loss coefficient Solar absorptance of collector Glazing transmittance Heat removal factor Air volumetric flow rate Specific heat of air Density of air 1200m2 600m2 800W/m2 8.0 W/m2K 0.9 0.8 0.6 9.80 m3/s 1.005kJ/kg-K 1.225kg/m3
Determine for the given conditions (option 2): (i) The collector efficiency. (10%) (ii) The useful energy delivered to the air passing through the solar air-heating system. (10%) (iii) The temperature change when air exits the solar air-heating system. (10%) (iv) The solar air-heating system operating conditions can be regarded as averages which are applicable to operating for 9 hours per day for 30 days each month. If the monthly heating load is 2.5TJ, determine the annual solar energy delivered and its percentage contribution? (10%) Data for Question-1 7- 1 n = Fzta - FUL t; -, 1. q=n1,4