Study material for Heating and Cooling Systems - Produzione di Energia Termica e Frigorifera, shared by the Studwiz community and reviewed by moderators.
Study material for Heating and Cooling Systems - Produzione di Energia Termica e Frigorifera, shared by the Studwiz community and reviewed by moderators.
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HEATING AND COOLING SYSTEMS 1st and 2nd year M.Sc. Energy Engineering Prof. L. Molinaroli ADDITIONAL EXERCISES Notice: All the missing data have to be assumed according to thermodynamic and/or engineering considerations. The thermodynamic consistency of the solution found should be checked (e.g. 1st law analysis at system level, no crossing of temperature profiles in the heat exchang- ers etc…). The properties of the refrigerants can be computed using Coolprop software. Vapour compression systems 1. Do the thermodynamic design of a vapour compression air-to-water heat pump that has to heat a water flow rate equal to ṁ = 5 kg/s from tWATER,IN = 30 °C to tWATER,OUT = 35 °C knowing that an air flow rate equal to v̇ = 40000 m3/h whose temperature is equal to tAIR,IN = -5 °C is used as secondary fluid at the evaporator. Consider a simple configuration system working with R32 and use the following equation to compute the compressor isentropic efficiency: ηISO = 0,4482 + 0,0637·β - 0,0071·β2 (β is the pressure ratio). 2. Do the thermodynamic design of a vapour compression water-to-water chiller that has to cool a water flow rate equal to ṁ = 25 kg/s from tWATER,IN = 23 °C to tWATER,OUT = 18 °C knowing that a water flow rate equal to ṁ = 30 kg/s, whose temperature is equal to tWATER,IN = 30 °C, is used as secondary fluid at condenser. Consider a simple configuration system working with R32 and use the following equation to compute the compressor isentropic efficiency: ηISO = 0,4482 + 0,0637·β - 0,0071·β2 (β is the pressure ratio). 3. Solve previous exercises considering advanced configurations such as LL-SLHX (εLL-SLHX = 0,5), two stages and, for the heat pump only, cascade with R32 in the bottom system and R1234yf in the top one. 4. Solve previous exercises considering a…
R32 8000 prof. Luca Molinaroli 7000 Dipartimento di Energia - Politecnico di Milano 80 °C 90 °C 100 °C 110 °C 120 °C 140 °C 160 °C Reference state: h = 200 kJ/kg e s = 1 kJ/(kg·K) for saturated liquid at T = 0 °C 6000 Data generated with Refprop 10.0 5000 70 °C 4000 60 °C 50 °C 3000 40 °C Pressure [kPa] 2000 30 °C 20 °C 10 °C 1000 900 800 0 °C 700 600 -10 °C 500 400 -20 °C 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 300 140 160 180 200 220 240 260 280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 Enthalpy [kJ/kg]
R1234yf 5000 prof. Luca Molinaroli Dipartimento di Energia - Politecnico di Milano 4000 Reference state: h = 200 kJ/kg e s = 1 kJ/(kg·K) 100 °C 110 °C 120 °C 130 °C for saturated liquid at T = 0 °C Data generated with Refprop 10.0 90 °C 3000 80 °C 70 °C 2000 60 °C 50 °C Pressure [kPa] 1000 40 °C 900 800 30 °C 700 600 20 °C 500 10 °C 400 0 °C 300 -10 °C 200 -20 °C 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 100 160 180 200 220 240 260 280 300 320 340 360 380 400 420 440 460 Enthalpy [kJ/kg]
R290 7000 prof. Luca Molinaroli 6000 Dipartimento di Energia - Politecnico di Milano 100 °C 110 °C 120 °C 130 °C 140 °C 150 °C Reference state: h = 200 kJ/kg e s = 1 kJ/(kg·K) 5000 for saturated liquid at T = 0 °C Data generated with Refprop 10.0 4000 90 °C 80 °C 3000 70 °C 60 °C 2000 50 °C 40 °C Pressure [kPa] 30 °C 1000 900 20 °C 800 700 10 °C 600 500 0 °C 400 -10 °C 300 -20 °C 200 -30 °C 0.10 0.20 0.30 0.40 -40 °C 0.50 0.60 0.70 0.80 0.90 100 80 120 160 200 240 280 320 360 400 440 480 520 560 600 640 680 720 760 800 Enthalpy [kJ/kg]
R744 15000 prof. Luca Molinaroli 14000 Dipartimento di Energia - Politecnico di Milano 40 °C 50 °C 60 °C 70 °C 80 °C 90 °C 100 °C 120 °C 140 °C 160 °C 13000 Reference state: h = 200 kJ/kg e s = 1 kJ/(kg·K) 12000 for saturated liquid at T = 0 °C Data generated with Refprop 10.0 11000 10000 9000 8000 30 °C 7000 6000 20 °C Pressure [kPa] 5000 10 °C 4000 0 °C 3000 -10 °C 2000 -20 °C -30 °C 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1000 100 150 200 250 300 350 400 450 500 550 600 Enthalpy [kJ/kg]
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