The book is called experimental method for engineer 8th edition. Problem 8.7. Le

Question

The book is called experimental method for engineer 8th edition. Problem 8.7. Let me know if you have the solution

A fluid-expansion thermometer uses liquid Freon (C = 0.22 Btu/lbm middot F, rho = 85.2 lbm/ft3) enclosed in a 0.25-in-ID copper (C = 0.092, rho = 560) cylinder with a wall thickness of 0.032 in. The thermometer is exposed to a cross flow of air at 400degreeF, 15 psia, and 20 ft/s. Estimate the time constant for such a thermometer. Neglect all effects of the capillary tube. Repeat for a cross flow of liquid water at 180degreeF and 20 ft/s. Recalculate the time constant for both of these situations for a stainless-steel bulb (C = 0.11, rho = 490).

Explanation / Answer

Every thermodynamic system has its own equation of state.For example,a system consisting of one gram mole of the gas at low pressure,has the equation of state

PV = RT

where R is the universal gas constant and V is molar volume.

At high pressure,the equation of state takes the form

(P + a/V^2) x (V - b) = RT

where a,b are Vander Waall's constant for the gas.

Let the internal energies in the initial and final states be Ui and Uf respectively.Applying the law of conservation of energy,we have

Uf - Ui = -W

where minus sign is introduced as the work is done on the system.The function U is know as internal energy function and is independent of path.So if a system undergoes a cyclic path and returns to the original condition,there is no change in its internal energy.

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.