(revised video available) Voltage required to evaporate ½ the water | Thermodynamics

Описание: PLEASE NOTE: We found an issue with the calculation of the last part of the problem and have thus revised the video. Here is the link to the revised video:    • Voltage required to evaporate ½ the water ...  
We thank our viewer Fish#1 for pointing it out

Welcome to Engineering Hack! In today's video we are solving a Thermodynamic's problem. We have a piston-cylinder device with 5 L of liquid water that is stirred by a paddle wheel while a current flows for 45 min through a resistor placed in the water, and we want to determine the voltage of the source, also show the process on a P-V diagram. The problem requires you to know that an insulated system can not receive or lose heat, the specific volume can be calculated dividing the volume by mass, quality can be calculated dividing mass of vapor by total mass and some other pure substance properties, such as the definition of enthalpy, which is (U + PdV). Everything else comes by analyzing the problem and the system at hand.

Problem statement: An insulated piston-cylinder device contains 5 L of saturated liquid water at a constant pressure of 175 kPa. Water is stirred by a paddle wheel while a current of 8 A flows for 45 min through a resistor placed in the water. If one-half of the liquid is evaporated during this constant-pressure process and the paddle-wheel work amounts to 400 kJ, determine the voltage of the source. Also, show the process on a P-V diagram with respect to saturation lines.

Answer:
a) 222 V

Link to property tables:
Water: https://drive.google.com/file/d/1n5El...

In this video:
00:00 Intro
00:38 Problem statement
01:20 Problem analysis
04:42 PV diagram
06:35 System energies
15:08 Flow energy
18:10 Enthalpy on state 1
20:26 Enthalpy on state 2
22:03 Enthalpy variation
22:49 Work of the electric system
26:48 Final Thoughts


🎓 Can you trust the answers and solutions provided? Well, you never should trust anything 100%. Make sure you are checking for yourself. When I’m solving the questions, I always solve on my own and then check the results against other sources. If there is divergence, I look for more sources. So while I can’t promise you everything will be 100% correct, I can promise I’ve done my due diligence before posting. If you enjoyed this video, please press the bell 🔔, like 👍,, comment or share. You're the best, thanks!
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