Piston cylinder Definition and 29 Threads

A piston is a component of reciprocating engines, reciprocating pumps, gas compressors, hydraulic cylinders and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas-tight by piston rings. In an engine, its purpose is to transfer force from expanding gas in the cylinder to the crankshaft via a piston rod and/or connecting rod. In a pump, the function is reversed and force is transferred from the crankshaft to the piston for the purpose of compressing or ejecting the fluid in the cylinder. In some engines, the piston also acts as a valve by covering and uncovering ports in the cylinder.

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  1. danut

    Ratio of volumes in a vertical cylinder with a piston

    First, I thought of the forces which are acting upon the piston. F1 + G = F2, where F1 = p1 * S and F2 = p2 * S p1 + mg/S = p2 I figured that before and after the gas' temperature rises, the piston has to be at equilibrium, so p2 - p1 = p2' - p1'. p1V1 = niu * R * T1 p2V2 = niu * R * T1 =>...
  2. Juanda

    Classical Possible error in book (Thermodynamics: An engineering approach)

    Hello I was checking the book THERMODYNAMICS AN ENGINEERING APPROACH (the 2023 version) because I saw it recommended on the internet. I was surprised to find an error in one of their examples because it is already on the 10th edition. I'm pretty sure about the error but I wanted to confirm it...
  3. T

    Total force from air spring model (double acting piston)

    Hi everyone, I'm an electrical engineer working on making a linear model for a power take-off system. I've gotten inertial, friction, and hydraulic/electric components done, but what is really confusing me is the gas system; I haven't taken ANY thermodynamics. To simplify it, it is modeled as a...
  4. questionmonkey123

    Constant pressure process (piston) on gas violates Newtons 2nd law?

    I often see this set up in thermodynamic problems and need clarification on how Newton's Laws are involved for the piston: Gas inside a piston cylinder (1) is heated expanding the gas and raising the piston (initially at rest) to a height (2) in a constant pressure quasi-equilibrium process...
  5. A

    Gas - cylinder - piston problem

    Summary:: Seeking explanation to classical gas - cylinder - piston problem, not the solution. Problem 1.15 from 7th edition of Introduction to Chemical Engineering Thermodynamics by Smith, Van nes and Abbot) Classical problem, given: - gas in a confined cylinder - piston with weight is placed...
  6. G

    Volume ratio in an adiabatic gas expansion

    Homework Statement Consider a perfect monoatomic gas at pressure $p_i$ 1.2 atm and temperature $T_i$ 300K, that is in equilibrium inside a cylinder having a volume $V_i=1L$ and which piston has a mass of 1kg and is at an height of 50 cm. Admit that a mass M=3.13kg is over the piston. When that...
  7. B

    Stationary vertical cylinder with heavy piston

    Hi, I'm just starting to learn thermodynamics and I'm completely stuck with a problem: 1. Homework Statement A stationary vertical cylinder, closed at the top, contains a gas whose volume may be changed with the aid of a heavy, frictionless piston of weight w. a) How much work is done by...
  8. EastWindBreaks

    Pressure of a piston cylinder device after heated

    Homework Statement I am confused on when will pressure of two states be the same for a piston cylinder device. Below are two problems where one's final pressure equals the initial pressure and one is not. Homework EquationsThe Attempt at a Solution Initially, I thought a piston-cylinder...
  9. R

    Programatically measure air pressure within a piston

    I am a software engineer. I am working on an experimental project to attempt to measure in real time the variation in air pressure (relative to the ambient pressure of the room) in a piston style apparatus. In this model, I am expectant that there will be a measureable change in the internal...
  10. Andrew Pierce

    Thermodynamics piston-cylinder closed system

    Homework 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...
  11. D

    Atmospheric Pressure on Shaft of piston cylinder assembly

    Homework Statement In a vertical piston cylinder assembly, a vertical shaft whose cross sectional area is 0.8 cm^2 is attached to the top of the piston. Determine the magnitude F, of the force acting on the shaft, in N, required if the gas pressure inside the cylinder is 3 bar. The masses of...
  12. Nemo's

    Calculate Pressure in piston cylinder after heating

    Homework Statement Water is contained in a cylinder fitted with a frictionless piston (figure shows that atmospheric pressure acts on piston from above). The mass of the water is 0.45 kg, and the piston area is 0.186 m2. Initially, the water conditions are 110oC and 90% dryness fraction, and...
  13. H

    Fluid solid interaction boundary condition problem

    I have come across the paper attached in which a 1D fluid piston is modeled. I have question on the boundary conditions (BCs) of the system. Essentially, the problem consists of a fluid chamber in contact with a spring (a mass -spring system). ALE is used to move the mesh. I am not certain...
  14. jdawg

    Finding work for a gas in a piston cylinder

    Homework Statement A gas in a piston-cylinder assembly undergoes a process for which the relationship between pressure and volume is pV2=Constant. The initial pressure is 1 bar, the initial volume is 0.1 m3, and the final pressure is 9 bar. Determine the final volume and the work for the...
  15. I

    Experiment on piston cylinder, issues with Ideal gas law

    Hello everyone, I have an rather large piston-cylinder containing gas that is compressed when the piston extends. Using three sensors I am measuring the pressure, temperature and volume of the gas while I force the piston out using a winch. The system is closed and no gas is released or added...
  16. N

    Change in u and h is for a piston cylinder device.

    Homework Statement 0.03m^3 of air is contained in the spring-loaded piston-cylinder device. The spring constant is 875N/m and the piston diameter is 25cm. When no force is exerted by the spring on the piston the state of the air is 2250kPa and 240C. This device is now cooled until the volume is...
  17. T

    Work & Final Temperature in Piston Cylinder (Check my work)

    If someone or a few people, just look this over and tell me if I'm right or if I did something wrong I'd be so grateful. I think it's all there but I'm not sure, there might be something off. Homework Statement Air (which behaves like an ideal gas) undergoes adiabatic expansion in piston...
  18. I

    Thermodynamics - Piston Cylinder

    A piston-cylinder device initially contains 1.4-kg saturated liquid water at 200 C. Now heat is transferred to the water until the volume quadruples and the cylinder contains saturated vapour only. Determine: (a) the volume of the tank, -> Use P1 = P2 to solve -> find Vg at 200oC (b) the...
  19. M

    Pressure in a piston cylinder assembly when both volume and temperature change

    I have a problem in relation to the pressure in a closed piston and cylinder assembly, I know the compression ratio and want to work out the pressure when the volume is at its lowest, boyles law only seems to works if the temperature remains constant but I know that as the piston moves and the...
  20. S

    Thermodynamics- piston cylinder- 2nd law of thermodyamics

    ( part a only I don't understand how you know from this question that it is a constant pressure process. I thought it is a polytropic process. So it will have a pVγ curve. I was drawing a pV curve. The answer is a straight line parallel to x- axis. My question: How do I know from...
  21. S

    Thermodynamics; Finding Work of a Piston cylinder Device

    Homework Statement An insulated piston-cylinder device contains 5 kg of water at 100oC with a quarter of the mass is vapor. The water is compressed reversibly to 900 kPa. Find the work done during this process. Let the ambient temperature to be 27oC. Homework Equations I can use the...
  22. X

    Concepts of a Piston cylinder device

    3.A cylinder/piston arrangement contains 5 kg of water at 100°C with x = 20% and the piston, mP = 75 kg, resting on some stops. The outside pressure is 100 kPa, and the cylinder area is A = 24.5 cm2. Heat is now added until the water reaches a saturated vapor state. Find the initial volume...
  23. S

    Intro thermodynamics question (simple piston cylinder)

    Homework Statement No need to include the figure, it's pretty much a piston sitting on some stops. Homework Equations Errmm...none I think The Attempt at a Solution My question is in regards to part c, and then part e. I know that in state 2 it's a superheated vapour...
  24. M

    Chemistry-TGhermodynamics Piston Cylinder Device question

    Homework Statement A piston cylinder device with a spring attached initially contains 0.02m^3 of R-134A at 50C. A valve connected to the cylinder is opened and 20kg of R-134A enters the device from a supply line at 800kPa and 80C. The spring is compressed and the piston moves up. The process...
  25. G

    Pressure or force in piston cylinder

    how can i find pressure or force in piston cylinder if i have... crank speend=5000rpm crank shaft throw=42mm piston diameter=95mm piston gudgeon mass=500g i know cylinder diameter=bore... is crank throw=stroke?
  26. N

    Pneumatic piston cylinder design

    Freinds, I have to design and simmulate a pneumatic piston cylinder, and want to calculate force profile of piston with time. please help me in this regard, also please tell me any simmulation software simmulating pneumatic piston cylinder.
  27. R

    Closed system piston cylinder device problem

    Homework Statement A closed system comprising a cylinder and frictionless piston contains 1kg of a perfect gas of which molecular mass is 26. The piston is loaded so that the pressure is constant at 200kPa. Heat is supplied causing the gas to expand from 0.5m^3 to 1m^3. Calculate heat...
  28. D

    Velocity of efflux in a piston cylinder arrangement.

    I did a few derivations to calculations to figure out the velocity of efflux off a pipe which is situated on the piston of a piston cylinder arrangement. Attached is the attempt...though I have a doubt in it - An attachment follows...can someone confirm if it's correct?
  29. T

    Thermodynamics Piston Cylinder Problem

    Homework Statement We were given a problem and asked to write a c++ program about this problem: A sample of gas is inside a piston cylinder arrangement initially at a temperature of 303K. The gas is leaked to a final temperature of 323K. According to the process PV^n=constant. The cylinder...
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