3) For process purposes a factory requires a supply of air at an atmospheric pressure of...

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3) For process purposes a factory requires a supply of air at an atmospheric pressure of 1.01325 bar and at 35C at a rate of 10 m/s for 16 h per day, 5 days per week, and 48 weeks per year. The average air temperature at entry is 11 C. Two heating systems are to be considered: a. Direct heating by a gas-fired heater which is 80% efficient and uses gas costing 0.015/k W h. b. A vapour-compression heat pump using Refrigerant 134a driven by an electric motor. The heat is taken from an outside source which has an average temperature over the year of 10 C. Assume electricity costs 0.05c/ kWh. Allow a 10 K temperature difference for heat transfer at the evaporator and condenser and assume a real coefficient of performance of 0.6 of that based on a simple heat pump cycle. Calculate: I. II. III. The average rate of heating required; The cost/annum for gas and electricity; The maximum difference in capital cost per kilowatt of heating load that can be spent if the pay-back period is to be less than 5 years. What other factors would you take into account before making a recommendation on the choice of installation? 3) For process purposes a factory requires a supply of air at an atmospheric pressure of 1.01325 bar and at 35C at a rate of 10 m/s for 16 h per day, 5 days per week, and 48 weeks per year. The average air temperature at entry is 11 C. Two heating systems are to be considered: a. Direct heating by a gas-fired heater which is 80% efficient and uses gas costing 0.015/k W h. b. A vapour-compression heat pump using Refrigerant 134a driven by an electric motor. The heat is taken from an outside source which has an average temperature over the year of 10 C. Assume electricity costs 0.05c/ kWh. Allow a 10 K temperature difference for heat transfer at the evaporator and condenser and assume a real coefficient of performance of 0.6 of that based on a simple heat pump cycle. Calculate: I. II. III. The average rate of heating required; The cost/annum for gas and electricity; The maximum difference in capital cost per kilowatt of heating load that can be spent if the pay-back period is to be less than 5 years. What other factors would you take into account before making a recommendation on the choice of installation?