Question

QUESTIONS 1. Refrigerant-134a is cooled by water in a condenser. The refrigerant enters the condenser at a pressure of 1 MPa and a temperature of 70°C at a flow rate of 6 kg / min and exits at a temperature of 35 °C. Cooling water enters the condenser at 300 kPa pressure and 15 °C temperature and exits at 25 °C temperature. By neglecting pressure losses, Calculate; a) mass flow of cooling water b) the heat transfer from the refrigerant to the water. 2. In a piston cylinder device with 5 kg of saturated vapor at 180 °C decreases its internal energy by 1/5 as a result of condensation at constant pressure. Then, x kJ/kg heat is transferred to the system at constant pressure and 74 kJ / kg work is done with the propeller in the cylinder. (x is taken last two number of each student number) a) Find the degree of quality of the fluid as a result of condensation. (5 POINTS) b) Find the total energy change in the system. (7 POINTS) c) Show the changes in the system by drawing the P-v diagram. Please indicate the values. (8 POINTS) 3. A rigid tank initially contains 0.32 kg steam at 4 MPa, superheated by 350°C. Now the steam loses heat to the surroundings and the cooling of tank continues until the cylinder contains water at x°C. Determine; (is the percentage of each student's number based on the last digit. For example, for 20171061 it is 100 °C) (a) the final pressure and the quality (if mixture), (b) the boundary work, (c) the amount of heat transfer (d) and the total entropy generation if the Tsur=20 °C. 4. A two-liquid pressure gauge is connected to a tank filled with water. In the environment where the warehouse is located, Patm = 755 mmHgs. The height of the liquids is h1 = 0.2m h2 = 0.3m h3 = 0.45m and the density of the water is 1000kg/m', the density of the oil is 0.85 and the density of the mercury is 13.6. Calculate the pressure of the air inside the tank. hava yag h! h3 civa

Answer 1

The given data in the question Medium 1 → R-bua Medium 2 → Water 70°C R-134a initial condition Pressure (Pii) = 1 MPn Temperature (Tip) From thermodynamic property table of R-34 at these condition the enthalpy of the medium Enthalpy Child 304 ks/ kg Pressure loss is negligible as per the question. i. Final R-134a conditions Pressure (P₂) 1 MPa Temperatur (TF1) = 35°C From the same thermodynamic table Enthalpy Chai) = 101 kJ/kg Mass flow rate mi 6 kg 1 min Water initial condition Pressure ( Piz) 300 kPa Temperature (Tiz) : 15°c

300 kPa From the thermodynamic property table of steam at these condition Enthalpy Chiz) = 63.3 kJ / kg At exit the water conditions are - Pressure (Pfz) Temperature (762) = 25° .: From the same table - Enthalpy Ch42) = 105 g/kg Suppose the mass flow rate of water is in Kg/min . By energy conservation law- Energy/Heat lost by R-by a = Energy / Heat gained by water . mix Chir-hi) = mx Chyz - hiz) (304–101) max (105-63.3 m = 20.21 kg/min 6 X र 486.8 gls

you need to upload the =2 For the next 2 questions value of '' Since question 4 has all the relevant data provided, I am solving that one, but I request you to upload one question at a time, because we have time constraints for each question. 4 Given data Almospheric pressure (Paton) = 755 mity =0.755 mito Water density - 1800 kg/m² W Marcury " Pm 13.6x1000 = 13600 kg/m3 o il Po 0.85 x 1000 =850 kg/m3 g=0.81 m/s Gravitational acceleration - :. At mospheric pressure Patm 0.7558 Pascal The setup

Patm Pair h hg A A 2 h

We will equate the pressure at A-A plane in 1st and 2nd coulma of the manometer - At 1 st contrrsh at AA plane Pressme PAA Pair + Pressure from water conlon for nieght hi (Pm) Pw = Puxgx hi 0.2x 23 Р. wXg At and conlmn at AA plane pressure - PAA' Patm + Pressure from marcury conlon of hight hz (Pm) - Pressure from oil contron of height h₂ (Po) Pm= Pmxgx h3 = 0.45X PmXg po Pc xgx hz = 0.3 x Poxg Equating these 2 [since at some height, the pressure remains constant Pair +0.2Pwg Patm +0.45pmg -0.3P 9 Parir = 0.755 fm 9 +0.45 pmg - 0.30.9 -0.2 Pwg

Pair ( 1.205pm - 0.3% -0.2 0.3. – 0.2Pw) % Putting all the values Pair 156.303 X10? Pa 156 : 303 kPa Pair An If you have any confusion with the solutions, ask me in the comments.