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3 years ago

Explain what entropy is in relation to the second law of thermodynamics?

Engineering

1 answer:

Marat540 [252]3 years ago

5 0

Explanation:

Second law tell us that ,the entropy of reversible process is remain constant while the entropy of ir-reversible process increases.

Entropy of universe is the summation of entropy of system and entropy of surrounding.So we can say that

$\Delta S_{universe}=\Delta S_{system}+\Delta S_{surrounding}$

Entropy can be define as

$ds=\int \dfrac{dQ}{T}$

Entropy is point function.This is property of system.Ir-reversibility cause the increase of entropy.

$\oint \dfrac{dQ}{T} =0 ,this\ is\ reversible\ process$

$\oint \dfrac{dQ}{T} >0 ,this\ is\ impossible\ process$

$\oint \dfrac{dQ}{T}$

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A cartridge electrical heater is shaped as a cylinder of length L=200mm and outer diameter D=20 mm. Under normal operating condi

lara31 [8.8K]

Answer:

T(water)=50.32℃

T(air)=3052.6℃

Explanation:

Hello!

To solve this problem we must use the equation that defines the transfer of heat by convection, which consists of the transport of heat through fluids in this case water and air.

The equation is as follows!

$Q=ha(Ts-T\alpha )$

Q = heat

h = heat transfer coefficient

Ts = surface temperature

T = fluid temperature

a = heat transfer area

The surface area of a cylinder is calculated as follows

$a=\pi D(\frac{D}{2} +L)$

Where

D=diameter=20mm=0.02m

L=leght=200mm)0.2m

solving

$a=\pi (0.02)(\frac{0.02}{2} +0.2)=0.01319m^2$

For water

Q=2Kw=2000W

h=5000W/m2K

a=0.01319m^2

Tα=20C

$Q=ha(Ts-T\alpha )$

solving for ts

$Ts=T\alpha +\frac{Q}{ha}$

$Ts=20+\frac{2000}{(0.01319)(5000)} =50.32C$

for air

Q=2Kw=2000W

h=50W/m2K

a=0.01319m^2

Tα=20C

$Ts=20+\frac{2000}{(0.01319)(50)}=3052.6C$

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3 years ago

sertanlavr [38]

Answer:

healthcare

Explanation:

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3 years ago

Subcooled liquid water flows adiabatically in a constant diameter pipe past a throttling valve that is partially open. The liqui

Llana [10]

Answer:

hi-he = 0

pi-pe = positive

ui-ue = negative

ti-te = negative

Explanation:

we know that fir the sub cool liquid water is

dQ = Tds = du + pdv ............1

and Tds = dh - v dP .............2

so now for process of throhling is irreversible when v is constant

then heat transfer is = 0 in irreversible process

so ds > 0

so here by equation 1 we can say

ds > 0

dv = 0 as v is constant

so that Tds = du .................3

and du > 0

ue - ui > 0

and

now by the equation 2 throttling process

here enthalpy is constant

so dh = 0

and Tds = -vdP

so ds > 0

so that -vdP > 0

as here v is constant

so -dP =P1- P2

so P1-P2 > 0

so pressure is decrease here

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3 years ago

James River Jewelry is a small jewelry shop. While James River Jewelry does sell typical jewelry purchased form jewelry vendors,

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