Hanoi University of Mining and Geology, HUMG
Chemical Engineering Laboratory, ECH 155A
Advanced Program K2

Determination of the exchanger effectiveness. NTU method


Instructor: Nguyễn Thị Linh Experiment’s day:29-7-2015
Student: Nguyễn Thị Lệ Thủy Deadline: 4-8-2015
ID: CTTT11210134
Group7: Nguyễn Thị Lệ Thủy
Nguyễn Thị Thu Trang
Trương Hải Thượng
Lê Vĩnh Thịnh



Table of content
Abstract
Appendices
Introduction
Theory
Experimental Methods
Results
Discussion and conclusions






1.Abstract
Through the experiment we can determine the exchanger effectiveness experimentally by using the NTU method. Besides, we can estimate the hot and cold water outlet temperature, we may compare with the measured values.
𝜀∆𝑇𝑚𝑖𝑛∆𝑇𝑚𝑎𝑥

q =
𝑞 𝑟𝑒𝑎𝑙
𝑞 𝑚𝑎𝑥

U.A
∆𝑇
𝑙𝑚
(∆𝑇1−∆𝑇2)/ln∆𝑇1∆𝑇2

NTU
U.A
m∗Cp
min

CR =
𝑚∗𝐶𝑝
𝑚𝑖𝑛
𝑚∗𝐶𝑝
𝑚𝑎𝑥

𝜀
,𝑖−,𝑜
,𝑖−𝑇𝑐,𝑖 if mh. Cp,h< mc. Cp,c
𝜀
𝑇𝑐,𝑜−𝑇𝑐,𝑖
,𝑖−𝑇𝑐,𝑖 if mc.Cp,c< mh. Cp,h

We have the result:
Two methods have the similar value
Value
Counter current
Parallel

𝜀
0.435685

0.402542


𝜀𝑁𝑇𝑈
0.460202

0.41587


Table 1: The efficiency







2.Appendices
Table 2: raw data

Counter current
Parallel

ST16(oC)
60
60

ST1
53.4
52.9

ST2
42.9
43.4

ST3
42.2
29.3

ST4
38.9
35

ST5
38.2
37.8

ST6
34.6
39

ST7
29.3
39.7

SC1(l/min)
2
2

SC2(l/min)
2
2


Flow
Mh(l/min)
Mc(l/min)
Th,i(oC)
Th,o(oC)
Tc,i(oC)
Tc,o(oC)

Counter
2
2
53.4
42.9
29.3
42.2

Parallel
2
2
52.9
43.4
29.3
39.7


3.Introduction
A heat exchanger is a device which allows heat transfer to happen between two fluids at different temperatures separated by a solid wall. The most simple is built with two concentric tubes, where fluids may either move in the same or in opposite direction. In parallel flow, hot and cold fluids may enter and leave at the same end while flowing in the same direction. In counter current flow fluids may enter and leave at opposite ends, flowing in opposite directions.
/
Parallel Counter current

Goal of the experiment: The main goal of this experiment is to determine the exchanger effectiveness experimentally as well as theoretically (by using the NTU method) and compare the two values. To estimate the hot and cold water outlet temperature, the students may compare with the measured values.
4.Theory
There are 3 types of heat exchanging: Conduction, convection and radiation
Conduction:
The conduction happens when heat transports through the thickness of the tube from the internal surface to the external surface. In dimensionless and stationary cases, heat transfer rate through a wall will be given by the following expression:
𝑞𝐾.𝐴
𝑇
2
𝑇
1
𝑥 (1)
Where: 𝑞 is the heat transfer rate (𝑤), 𝐾 is thermal conductivity of the wall
𝑤
𝑚.𝐾), 𝐴 is the perpendicular area to the direction of heat flow
𝑚
2), 𝑙 is the wall thickness (𝑚),
𝑇
2 is the temperature on the cold surface of the wall (𝐾),
𝑇
1 is the temperature on the hot surface of the wall (𝐾).
Convection:
The heat transfer mode between a surface and a fluid in motion which are at different temperature. The convection heat transfer rate of surface and a fluid is given by Newton`s law of cooling, which is expressed as: 𝑞=𝐴.ℎ
𝑇
𝑠
𝑇) (2)
Where 𝑞 is the convection heat transfer rate (𝑤), ℎ is the convection heat transfer coefficient
𝑤
𝑚
2.𝐾𝐴 is the heat transfer area
𝑚
2),
𝑇
𝑠 is the surface