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QUESTION 3 In the Swiss Alps, nearby the village Stechelberg, a hydroelectric power plant has been operating since 1905. The water is tapped from a very wide reservoir and then flows down through a single so-called pressure line to the (Pelton) turbines. This pressure line is 70 cm in diameter. The difference in elevation between the surface of the reservoir and the turbines amounts to 250 m. Under steady-state conditions, the volumetric flow rate through the pressure line is 1.1 m/s. Due to the friction in the pressure line, the water temperature just upstream of the turbines is 4.5 103 K higher than the water temperature in the reservoir. The specific heat of water is 4.2 kJ/kgK. Heat exchange with the surroundings may be ignored. a) Calculate how much energy is dissipated per kg of water as a consequence of the water flow through the pressure line? And how large is the associated power loss for the power plant? [9 marks] b) Calculate the absolute) pressure just upstream of the turbines. To this end, select the proper energy balance and report which one you select. Indicate clearly, also in your sketch, between which points you draw up this energy balance. Use here g = 9.81 m/s. [21 marks] [Total: 30 marks]