General thermodynamic equations

Question 1

mass flow rate, m. =

Answer 1

m. = ρAv

ρ density
v velocity

Question 2

Isothermal

Answer 2

temperature remains constant

Question 3

Adiabatic

Answer 3

heat does not enter or leave system

Question 4

Equation for outlet temperature of water flow down a heated tube

Answer 4

Tout = Ts - (Ts - Tin)exp( - As.h / mc(p))

Ts = surface temp of tube
Tin = temp of fluid inlet
As = surface area of tube = 2pi r L
m = ρ V = density * volumetric flow rate = mass flow rate
̇

Question 5

What does LMTD stand for

Answer 5

Log mean temperature difference

Question 6

Equation for LMTD

Answer 6

= ΔT1 - ΔT2 / ln(ΔT1/ΔT2)

Question 7

What is the critical heat flux

Answer 7

Point where heat flux reached no longer increases as insulation is added
Insulation thickness larger than critical heat flux is recommended

Question 8

Equation for radius at critical heat flux

Answer 8

r crit = k / h

Question 9

Equation for h (combined)

Answer 9

h(combined) = h(conv) + h(rad)

h(combined) = h(conv) + εσ(Ts^2 - Tsurr^2)(Ts - Tsurr)

Question 10

Number to get R in equation for density of gas

Answer 10

8314/R(inLBOTF)

Question 11

Equation for T for a long pipe with an insulated surface at r(out)

Answer 11

T = q/4K * (r(out)^2 - r^2) - q/2K * r(out)^2 * ln(r(out)/r) + Tout

Question 12

Grassoff number

Answer 12

Gr = gρ^2B(Ts - T∞)L^3/µ^2

B = 1/Tfilm

Ra = GrPr