**Subject:** Thermodynamics **Topic:** Ammonia Absorption Refrigeration Cycle (Powered by Solar Energy) --- ### **Step 1: Given Data and Conceptual Introduction** **Given Data:** - Saturated vapor ammonia leaves the generator at \( T_{gen} = 50^\circ C \) - Saturated vapor leaves the evaporator at \( T_{evap} = 10^\circ C \) - Heat supplied to generator per 1 kg ammonia vapor generated: \( Q_{in, gen} = 3000 \) kJ/kg **Conceptual Introduction:** Ammonia absorption refrigeration systems use heat (here, solar energy) to drive the cycle instead of mechanical work. The system's performance is measured by the coefficient of performance (COP), which is the ratio of refrigeration effect to input heat. **Explanation block:** The absorption refrigeration cycle uses thermal energy to create cooling by absorbing and desorbing ammonia in a solution. The COP tells us how efficiently the system converts the input heat into useful cooling. --- ### **Step 2: Step-by-step Calculation Part** #### **Step 2.1: Find Refrigeration Effect (per kg ammonia)** - The refrigeration effect is the amount of heat absorbed in the evaporator per kg of ammonia. From ammonia tables: - At \( T_{evap} = 10^\circ C \): - \( h_{g,10^\circ C} \) (Enthalpy of saturated vapor) \( \approx 1466 \) kJ/kg - At \( T_{gen} = 50^\circ C \): - \( h_{f,50^\circ C} \) (Enthalpy of saturated liquid) \( \approx 322 \) kJ/kg **Refrigeration Effect, \( q_{evap} \):** \[ q_{evap} = h_{g,10^\circ C} - h_{f,50^\circ C} \] \[ q_{evap} = 1466 - 322 = 1144 \ \text{kJ/kg} \] **Explanation block:** We use enthalpy values for saturated vapor at the evaporator and saturated liquid at the generator, since the refrigerant absorbs heat in the evaporator and is condensed in the absorber/generator. --- ### **Step 3: Overall System Performance** #### **Step 3.1: Coefficient of Performance (COP) Calculation** \[ COP = \frac{\text{Refrigeration Effect}}{\text{Heat supplied to Generator}} \] \[ COP = \frac{q_{evap}}{Q_{in,gen}} \] \[ COP = \frac{1144}{3000} = 0.381 \] **Explanation block:** The COP for absorption systems is the ratio of cooling provided to the heat energy supplied, reflecting system efficiency. Here, it shows how much cooling is produced per unit of solar heat input. --- ### **Final answer** **Final answer:** The overall performance (COP) of this ammonia absorption refrigeration system is **0.38** (rounded to two decimal places).