2b) Determine chemical formula of the following refrigerants

Here are the solutions to your problems: 2b) Determine chemical formula of the following refrigerants (i) R12: CCl_2F_2 (Dichlorodifluoromethane) (ii) R22: CHClF_2 (Chlorodifluoromethane) (iii) CO_2: CO_2 (Carbon dioxide) (iv) NH_3: NH_3 (Ammonia) (v) H_2O: H_2O (Water) 3) A Freon 12 vapour compression system operating at a condenser temperature of 40^ and evaporator temperature of -5^ develops 15 tons of refrigeration. To solve this problem, a P-h diagram for Freon 12 (R12) is required to determine the specific enthalpy (h) and specific volume (v) values at different points in the cycle. Since the diagram is not provided, I will outline the steps and formulas. Given Data: Refrigerant: Freon 12 (R12) Condenser temperature, T_c = 40^ Evaporator temperature, T_e = -5^ Refrigeration capacity, Q_e = 15 tons of refrigeration (TR) Conversion: 1 ton of refrigeration (TR) = 3.517 kW Q_e = 15 TR × 3.517 kWTR = 52.755 kW Cycle Points (from P-h diagram): State 1 (Evaporator outlet, compressor inlet): Saturated vapor at T_e = -5^. Read h_1 (enthalpy), v_1 (specific volume), s_1 (entropy) from the diagram. State 2 (Compressor outlet, condenser inlet): Superheated vapor after isentropic compression from State 1 to the condenser pressure (corresponding to T_c = 40^). Follow an isentropic line (s_2 = s_1) from State 1 to the condenser pressure. Read h_2. State 3 (Condenser outlet, expansion valve inlet): Saturated liquid at T_c = 40^. Read h_3 from the diagram. State 4 (Expansion valve outlet, evaporator inlet): Liquid-vapor mixture after isenthalpic expansion from State 3. h_4 = h_3. Calculations: i) Mass flow rate of refrigerant circulated (m): The refrigeration capacity is given by: Q_e = m(h_1 - h_4) m = (Q_e)/(h_1 - h_4) Numerical value cannot be determined without h_1 and h_4 from the P-h diagram. ii) Theoretical piston displacement of the compressor (V) and piston displacement per ton of refrigeration: The theoretical piston displacement is: V = m · v_1 Piston displacement per ton of refrigeration: VTR = m · v_1Q_e/TR Numerical values cannot be determined without m and v_1 from the P-h diagram. iii) Theoretical horse power of the compressor (W_c) and horse power per ton of refrigeration: The theoretical compressor work is: W_c = m(h_2 - h_1) To convert to horsepower (HP), use 1 HP = 0.7457 kW: W_c (HP) = m(h_2 - h_1)0.7457 Horse power per ton of refrigeration: W_c (HP)TR = W_c (HP)Q_e/TR Numerical values cannot be determined without m, h_1, and h_2 from the P-h diagram. iv) Heat rejected in the condenser (Q_c): The heat rejected in the condenser is: Q_c = m(h_2 - h_3) Numerical value cannot be determined without m, h_2, and h_3 from the P-h diagram. v) Carnot COP and actual COP of the cycle: Carnot COP (COP_Carnot): Convert temperatures to Kelvin: T_e = -5^ + 273.15 = 268.15 K T_c = 40^ + 273.15 = 313.15 K COP_Carnot = (T_e)/(T_c - T_e) = 268.15 K313.15 K - 268.15 K = (268.15)/(45) ≈ 5.959 Actual COP (COP_actual): COP_actual = (Q_e)/(W_c) = m(h_1 - h_4)m(h_2 - h_1) = (h_1 - h_4)/(h_2 - h_1) Numerical value cannot be determined without h_1, h_2, and h_4 from the P-h diagram.