One who is trained in math, science and physics in order to work in a branch of engineering

A counter-flow double-piped heat exchange is to heat water from 20oC to 80oC at a rate of 1.2 kg/s. The heating is to be accompl

lawyer [7]

Answer:

110 m or 11,000 cm

Explanation:

let mass flow rate for cold and hot fluid = Mc and Mh respectively
let specific heat for cold and hot fluid = Cpc and Cph respectively
let heat capacity rate for cold and hot fluid = Cc and Ch respectively

Mc = 1.2 kg/s and Mh = 2 kg/s

Cpc = 4.18 kj/kg °c and Cph = 4.31 kj/kg °c

Using effectiveness-NUT method

First, we need to determine heat capacity rate for cold and hot fluid, and determine the dimensionless heat capacity rate

Cc = Mc × Cpc = 1.2 kg/s × 4.18 kj/kg °c = 5.016 kW/°c

Ch = Mh × Cph = 2 kg/s × 4.31 kj/kg °c = 8.62 kW/°c

From the result above cold fluid heat capacity rate is smaller

Dimensionless heat capacity rate, C = minimum capacity/maximum capacity

C= Cmin/Cmax

C = 5.016/8.62 = 0.582

.2 Second, we determine the maximum heat transfer rate, Qmax

Qmax = Cmin (Inlet Temp. of hot fluid - Inlet Temp. of cold fluid)

Qmax = (5.016 kW/°c)(160 - 20) °c

Qmax = (5.016 kW/°c)(140) °c = 702.24 kW

.3 Third, we determine the actual heat transfer rate, Q

Q = Cmin (outlet Temp. of cold fluid - inlet Temp. of cold fluid)

Q = (5.016 kW/°c)(80 - 20) °c

Qmax = (5.016 kW/°c)(60) °c = 303.66 kW

.4 Fourth, we determine Effectiveness of the heat exchanger, ε

ε = Q/Qmax

ε = 303.66 kW/702.24 kW

ε = 0.432

.5 Fifth, using appropriate effective relation for double pipe counter flow to determine NTU for the heat exchanger

NTU = $\\ \frac{1}{C-1} ln(\frac{ε-1}{εc -1} )$

NTU = $\frac{1}{0.582-1} ln(\frac{0.432 -1}{0.432 X 0.582 -1} )$

NTU = 0.661

.6 sixth, we determine Heat Exchanger surface area, As

From the question, the overall heat transfer coefficient U = 640 W/m²

As = $\frac{NTU C{min} }{U}$

As = $\frac{0.661 x 5016 W. °c }{640 W/m²}$

As = 5.18 m²

.7 Finally, we determine the length of the heat exchanger, L

L = $\frac{As}{\pi D}$

L = $\frac{5.18 m² }{\pi (0.015 m)}$

L= 109.91 m

L ≅ 110 m = 11,000 cm

3 0

3 years ago

What is the first step necessary for initiating the visual transduction cascade in rods?.

irinina [24]

'Capturing a photon by isomerization and rhodopsin of retinal' is the first step necessary for initiating the visual transduction cascade in rods.

Visual transduction refers to the process in the eye where absorption of light in the 'retina' is translated into electrical signals that then reach the brain. It is correct to state that visual transduction is the photochemical reaction that takes place when light or photon is converted to an electric signal in the retina. The visual pigment in the rods, called rhodopsin, is a membrane protein placed in the outer segments of the rods.

When initiating the visual transduction cascade in rods the first vital step is to capture a photon by isomerization and rhodopsin of retinal'.

You can leran more about visual transduction at

brainly.com/question/13798113

#SPJ4

4 0

1 year ago

Tech A says that failure of a battery hold down can cause battery plate damage. Tech B says that a bungee

Pavel [41]

Answer:

Technician A

Explanation:

1- It's was easy to understand.

2- Holding down a battery could actually cause battery plate damage. Most of the batteries I interact with only use a plastic cover and a small spring to hold the battery in place.

-Hope this helped :) -

7 0

3 years ago

Question 6: Which of the following is NOT true if you are changing into a

baherus [9]

Answer:

You should activate your signals 100 feet before you turn, becuase of that you should not wait until you are turning to turn on your signals. If you do not have working lights use your hands. So the answer that is inccorect is B.

You should activate your signals when you get into the turn lane is NOT true

Because you are supposed to single beforhand not while you're in the lane.

Im taking my drivers ed too. :)

6 0

3 years ago

What is the first thing a person must do before anything can be done today corroded area

melamori03 [73]

Answer:

Explanation:

We have learned that three things are required for the anodic and cathodic steps of corrosion to occur: an electrolyte, an exposed metal surface, and an electron acceptor. It follows, then, that we can prevent corrosion by removing one of these essential conditions.

8 0

2 years ago