4.An inventor claims to have developed a device that executes a power cycle while operating between reservoirs at 500 and 300 K that has a thermal efficiency of 40% . Is it possible? Why? (15%)

5.A small nuclear reactor is cooled by passing liquid sodium (Na) through it. The liquid sodium leaves the reactor at 0.2 MPa and 400°C. It is cooled to 320°C by passing through a heat exchanger before returning to the reactor. In the heat exchanger, heat is transferred from the liquid sodium to water, which enters the exchanger at 10 MPa and 49°C(enthalpy is 176.38 kJ/kg) and leaves at the same pressure as a saturated vapor (enthalpy is 2724.7 kJ/kg). The mass flow rate of sodium is 10,000 kg/h, and its specific heat is constant at L25J/(g)(°C). Determine the mass flow rate of water evaporated in the heat exchanger, in kg/h, and the heat-transfer rate between the two fluids, in kJ/h. (15%)

6.A gearbox operating at steady state receives 20 horsepower along its input shaft，delivers power along its output shaft，and is cooled on its outer surface according to Q = - h A (Tb - T0 )，where =110°F is the temperature of the outer surface and T。= 40°F is the temperature of the surroundings far from the gearbox. The product of the heat transfer coefficient h and outer surface area A is 35 Btu/h*R. For the gearbox, determine the power delivered along the output shaft，the rate of availability transfer accompanying heat， and the irreversibility rate, each in Btu/h. Express each quantity as a percentage of the input power.

一、

二、

三、

(1)

(2)

(3)

(4)

(5)

110年 - [無官方正解]110 國立臺北科技大學_碩士班招生考試_資源工程研究所：基礎熱力學#139411

110年 - 110 國立臺灣科技大學_碩士班招生試題_材料科學與工程系(丙組)：熱力學#113287

110年 - 110 國立清華大學碩士班考試入學試題_工程與系統科學系/乙組:熱力學#105638

110年 - 110 國立臺北科技大學_碩士班招生考試_能源與冷凍空調工程系(乙組)：熱力學#105572

110年 - 110 高雄科技大學_碩士班招生考試_化學工程與材料工程系：熱力學(丙組)#104400

110年 - 110 國立中央大學_碩士班招生考試_機械工程學系/熱流組(一般生):熱力學#103851

110年 - 110 國立臺北科技大學_碩士班招生考試_車輛工程系：熱力學#101959

110年 - 110 國立臺灣大學_碩士班招生考試_應用力學研究所乙組:熱力學(C)#101258

110年 - 110 國立臺灣大學_碩士班招生考試_材料科學與工程研究所乙組:熱力學(B)#100917

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