An air-standard cycle with constant specific heats at room temperature is executed in a closed system with 0.0025 kg of air and consists of the following three processes:

1–2 v = Constant heat addition from 95 kPa and 17°C to 380 kPa
2–3 Isentropic expansion to 95 kPa
3–1 P = Constant heat rejection to initial state
The properties of air at room temperature are cp = 1.005 kJ/kg·K, cv = 0.718 kJ/kg·K, and k = 1.4.

(a) Show the cycle on P-v and T-s diagrams.
(b) Calculate the net work per cycle, in kJ.
(c) Determine the thermal efficiency.

Determine the time of the day and month of the year at which the peak sensible cooling load occurs for a top floor, north-eastern corner room of an office building in durban for the following conditions: floor area: 8 x 8 x 3 m east and north walls: 115 mm face brick (outside), 20 mm air space, 115 mm ordinary brick (inside) with 15 mm plaster roof construction: suspended plasterboard ceiling, 450 mm air space, 150 mm concrete, 75mm screed, waterproofing no heat transfer across other surfaces window area 3x 1,5 m high in north wall only. ordinary glass with venetian blinds. lights and occupants : from 07: 00 to 18: 00 average light density: 25 w/m2 number of occupants : 5 seated, light office work room temperature 24°c