A cinema hall for the 150 persons has 10 wall fans, each consuming 0.15 kW of power, and a 5100 W lamp. The air enters through the ventilation at the rate of 81 kg/h with the enthalpy of 87 kJ/kg and leaves through another ventilation with the enthalpy of 54 kJ/kg. If each person puts out heat at a rate of 600 kJ/hr. If the heat removed from the hall by an air cooler is at a rate of 1.8495 kW then the number of such air coolers that will be required in the cinema hall so that a steady state can be maintained in the hall?