Problem Solving Strategy: Heat engines IDENTIFY the relevant concepts. A heat engine is any device that converts heat pa

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Problem Solving Strategy Heat Engines Identify The Relevant Concepts A Heat Engine Is Any Device That Converts Heat Pa 1 (97.31 KiB) Viewed 53 times

Problem Solving Strategy: Heat engines IDENTIFY the relevant concepts. A heat engine is any device that converts heat partially to work SET UP the problem using the following steps Learning Goal: Steam at a temperature Tu = 310 °C and p = 1.00 atm enters a heat engine at an unknown flow rate. After passing through the heat engine, it is released at a temperature Tc = 100 °C and p = 1.00 atm The measured power output P of the engine is 550 J/s, and the exiting steam has a heat transfer rate of Hc = 2200 J/s Find the efficiency e of the engine and the molar flow rate n/t of steam through the engine. The constant pressure molar heat capacity Cp for steam is 37.47J/(mol. K) 1. Carefully define what the thermodynamic system is 2 For multi-step processes with more than one step, identify the initial and final states for each step 3. Identify the known quantities and the target variables. 4. The first law. AU=Q-W, can be applied just once to each step in a thermodynamic process, so you will often need additional equations. The equation W Qс Qc e = = 1+ 1- QH QH QH is useful in situations for which the thermal efficiency of the engine is relevant. It's helpful to sketch an energy-flow diagram. EXECUTE the solution as follows: 1. Be very careful with the sign conventions for W and the various Q's W is positive when the system expands and does work, W is negative when the system is compressed. Each Q is positive if it represents heat entering the system and is negative if it represents heat leaving the system 2. Power is work per unit time (P=W/t), and heat current His heat transfer per unit time (H=Q/t). 3. Keeping steps 1 and 2 in mind, solve for the target variables EVALUATE your answer Use the first law of thermodynamics to check your results, paying particular attention to algebraic signs IDENTIFY the relevant concepts This heat engine partially converts heat from the incoming steam into work, so the problem solving strategy for heat engines is applicable SET UP the problem using the following steps

The heat transfer rate for steam leaving the engine, HC The temperature of steam as it leaves the engine. To The constant pressure molar heat capacity of steam, Cp Learning Goal: Steam at a temperature Tu = 310 °C and p = 1.00 atm enters a heat engine at an unknown flow rate. After passing through the heat engine, it is released at a temperature Tc = 100 °C and p = 1.00 atm. The measured power output P of the engine is 550 J/s, and the exiting steam has a heat transfer rate of Hc = 2200 J/s Find the efficiency e of the engine and the molar flow rate n/t of steam through the engine. The constant pressure molar heat capacity C, for steam is 37.47 J/(mol-K) The molar flow rate of steam n/t The heat transfer rate for steam entering the engine. Hy The efficiency of the engine, e Submit Request Answer EXECUTE the solution as follows Part B Complete previous part(s) Part C Complete previous part(s) EVALUATE your answer Part D Complete previous part(s)