110年 - 110 國立臺灣大學_碩士班招生考試_生物機電工程學研究所乙、戊組: 熱力學(D)#100913

(a) (5%) The specific humidity of the air in the space

(b) (5%) The maxirnumn remiperature of the surface to dehumldiry the atr in the space

(c) (5%) When the direct evaporative cooling is applied in the space, how many degrees of the maximum temperature drop can be achieved?

(a) (5%) Suppose you want to operate an ideal refrigerator with a cold temperature of -10.0℃, and you would like it to have a coefficient of performance of 7.00. What is the hot reseryoir temperature for such a refrigerator?

(b) (5%) What is the best coefficient of performance for a heat pump that has a hot reservoir temperature of 50.0℃ and a cold reservoir temperature of -20.0℃? (5%) How much heat transfer occurs into the warm environment if 3.60 x 10⁷ J of work is put into it?

3. Please derive (a) (8%) the Joule-Thomson coefficient and (b) (7%) the inversion temperature for a gas whose equation of state is

(a) (8%) The final temperature.

(b) (7%) The amount of mass that escapes the tank. For nitrogen, MPa. Please state clearly all of your assumptions.

5. (10%) The ambient temperature in an outdoor ice-skating rink is at -5℃. How much force should one exert to skate smoothly at this temperature if the width and length of the skate blade are 1 min and 30 cm ? Assume that enthalpy of fusion for water is 333.55 J/g. The density of water and ice at this temperature are assumed 1000 kg/m³and 917.5 kg/m³. Please state clearly all of your assumptions.

(a) (10%) Derive the net work per cycle in terms of C_ν, temperature, and compression ratio Rc.

(b) (8%) What is the compression ratio value to achieve the maximum work per mass of air?

(c) (7%) Express the intermediate temperature T₂ and T₄ in (b) in terms of T₁ and T₃.

(d) (5%) What is the maximum theoretical efficiency of this engine if the fuel-air mixture is initially at 25℃ and the mixture is compressed by a factor of 7.8?

110年 - 110 國立臺灣大學_碩士班招生考試_生物機電工程學研究所乙、戊組: 熱力學(D)#100913

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