管壳式热交换器的流体流动英文文献和中文翻译
many systems. A heat exchanger is a device built for efficient heat transfer from one medium to
another in order to carry and process energy. Typically one medium is cooled while the other is
heated. They are widely used in petroleum refineries, chemical plants, petrochemical plants,
natural gas processing, air-conditioning, refrigeration, and automotive applications. One com-
mon example of a heat exchanger is the radiator in a car, in which it transfers heat fromthe water
(hot engine-cooling fluid) in the radiator to the air passing through the radiator.7681
There are two main types of heat exchangers:
– direct contact heat exchanger, where both media between which heat is exchanged are in
direct contact with each other, and– indirect contact heat exchanger, where both media are separated by a wall through which
heat is transferred so that they never mix.
A typical heat exchanger, usually for higher pressure applications up to 552 bar, is the
shell and tube heat exchanger. Shell and tube type heat exchanger is an indirect contact type heat
exchanger as it consists of a series of tubes, through which one of the fluids runs. The shell is a
container for the shell fluid. Usually, it is cylindrical in shape with a circular cross-section, al-
though shells of different shapes are used in specific applications. For this particular study E
shell is considered, which is generally a one pass shell. E shell is themost commonly used due to
its low cost and simplicity, and has the highest log-mean temperature-difference (LMTD) cor-
rection factor. Although the tubes may have single or multiple passes, there is one pass on the
shell side, while the other fluid flows within the shell over the tubes to be heated or cooled. The
tube side and shell side fluids are separated by a tube sheet, [1-3]. The heat exchanger model
used in this study is a small sized one, as compared to the main stream, all of the leakage and by-
pass streams do not exist or are negligible, [4-6]. Baffles are used to support the tubes for struc-
tural rigidity, preventing tube vibration and sagging and to pert the flow across the bundle to
obtain a higher heat transfer coefficient. Baffle spacing (B) is the centre line distance between
two adjacent baffles, [7-9]. Baffle is provided with a cut (Bc) which is expressed as the percent-
age of the segment height to shell inside diameter. Baffle cut can vary between 15% and 45% of
the shell inside diameter, [10-12]. In the present study 36% Bc is considered. In general, con-
ventional shell and tube heat exchangers result in high shell-side pressure drop and formation of
re-circulation zones near the baffles.Most of the researches now a day are carried on helical baf-
fles, which give better performance then single segmental baffles but they involve high manu-
facturing cost, installation cost and maintenance cost. The effectiveness and cost are two impor-
tant parameters in heat exchanger design. So, In order to improve the thermal performance at a
reasonable cost of the shell and tube heat exchanger, baffles in the present study are provided
with some inclination in order tomaintain a reasonable pressure drop across the exchanger [13].
The complexity with experimental techniques involves quantitative description of
flow phenomena using measurements dealing with one quantity at a time for a limited range of
problem and operating conditions. Computational fluid dynamics (CFD) is now an established
industrial design tool, offering obvious advantages [14]. In this study, a full 360° CFD model of
shell and tube heat exchanger is considered. By modeling the geometry as accurately as possi-
ble, the flow structure and the temperature distribution inside the shell are obtained.