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Lana71 [14]
3 years ago
6

A 2"" Sch 40 stainless steel (k = 14.9 W/m-K) pipe is to be used as the interior pipe of a double pipe heat exchanger. The expec

ted heat transfer coefficients of the hot and cold fluids are 1800 W/m2-K and 1600 W/m2-K respectively. Determine the total resistance to heat flow per unit length (i.e. R  L) with and without the resistance of the pipe wall. What is the percentage difference? (18.2%)
Engineering
1 answer:
Scrat [10]3 years ago
8 0

Answer:

the percentage difference is E = = 55.7% respect to the real value ( with resistance of the wall)

Explanation:

the resistance to heat flow R is

R=  ( 1/h₁ + ln (re/ri)/(2π*k*L) + 1/h₂)

where

h₁= heat transfer coefficient for the hot fluid = 1600 W/m²K

h₂= heat transfer coefficient for the cold fluid = 1800 W/m²K

re/ri = ratio between external radius and internal radius of the pipe = 2.375 /2.067  for 2"" Sch 40 stainless steel

k= thermal conductivity = k = 14.9 W/m-K

L = length of the pipe = 1 ( unit length)

therefore replacing values

R₁=  1/h₁ + ln (re/ri)/(2π*k*L) + 1/h₂ = 1/1600 W/m²K + ln(2.375 /2.067)/(2π*14.9 W/m-K*1) + 1/1800 W/m²K = 2.664 *10⁻³m²K/W

when the resistance of the pipe wall is neglected then R would be

R₂=  1/h₁ + 1/h₂ =  1/1600 W/m²K 1+ 1/1800 W/m²K =1.180 *10⁻³ m²K/W

the percentage difference between the total resistance with and without the pipe wall resistance per unit length  is

E = 1-(R₂/L) /( R₁/L) = 1- R₂/R₁=1- (1.180 *10⁻³/2.664 *10⁻³) = 0.557= 55.7%

E = = 55.7%

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Answer:

The engineers disagreed because their jobs were on the line

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Explanation:

The engineers disagree because there is no direct connection between the company's loss of the customer and their proposed layoff of the engineers,at least no one strong evidence has been given by the president.

The ethical factors inherent in this case are as follows:

The reason for the customer dumping the business is yet to be figure out

The need to keep cost to the lowest ebb in order to keep maintain profitability.

The are several ways of growing customer base which  are yet to be exploited.

There is  a need for a fact-finding exercise to establish the main motive behind losing such customer,without which the company can run into more troubles in future,otherwise the company would keep firing its good hands each time a customer dumps it.

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Explanation:

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The given blanks can be filled as given below

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