A Heat exchanger is an essential thermal machine
ingunitscondens | 29 Avgust, 2019 05:47A Heat exchanger is an essential thermal machine employed for industrial
cooling, with several types existing: shell and tube, plate exchangers, spiral
heat exchanger, block and fin heat exchangers. Heat exchangers are crucial
equipments for industrial thermoregulation, but also required in residential and
commercial air-conditioning plants, achieving heat transfer between two fluids
with different temperatures: Water Cooled Evaporators heat exchangers are indeed passive thermal
machines, allowing the transfer of heat energy between fluids, thanks to an
existing temperature gap.
In a plate heat exchanger, the fluids are
separated by a thin metallic screen, a plate, wich allows the heat transfer
between the two fluids flowing on its sides separately. Corrugated plates
increase thermal transfer, extending exchanging surface area and boosting energy
dissipation thanks to turbulence prompted in flowing fluids and higher
transmission coefficients.
The cold fluid gets heated in contact with the
plate, gaining heat from the fluid to be cooled, and is then carried to a
cooling system (a chiller, or dry cooler or evaporative towers, for example),
bringing the fluid at a lower temperature.
Plate Heat exchangers offer
several advantages, being compact and smaller, and easily sizable, also to fit
new and changed working project conditions leading to a higher thermal duty,
with an increased thermal load to be managed. Strengthening a heat exchanger is
indeed achieved simply adding new plates, in order to answer a growth in
production, and then a growth in the quantity of heat generated, or due to
changes in the thermal conditions of the cooling cycle, for example laking of
cooling air or water at a certain temperature, meaning a loss in dissipating
capacity of the cooling system itself.
It's plain that is possible to
strengthen an existing heat exchanger only in case of an openable and
inspectable gasketed exchanger. If a brazed plate exchanger was the first
project choice, it won't be possible to increase the thermal load capacity once
it is installed, and an alternative solution has to be found to manage an
increased thermal duty (adding others exchangers, more powerful or bigger
exchangers).
In a plate inspectable heat exchanger is easy to vary the
thermodinamic state of the machine, adding new plates to the existing ones,
increasing thermal transfer surface area having extra dissipating capacity.
Transfer heat surface area needed to perform the thermal duty in a heat
exchanger is usually calculated in function of exchange process characteristics
and thermophysical properties of the fluids. Speaking of strengthening an
existing heat exchanger, kind of fluids and thermal process are supposed to
remain the same, and the only variable is the amount of heat load the machine
has to dissipate, or also a new temperature gap between the
fluids.
Strengthening a plate heat exchanger is then a quite simple
operation, only requiring a correct evaluation of the new thermal load or the
new fluids temperatures, in order to determine the right additional thermal
transfer surface area and the number of plates that can be inserted to obtain
the thermal performance needed.
Strengthening a heat exchanger requires a
series of operations, that in the same time allow to check operability and
affordability of the exchanger, and in case regenerating it cleaning and
changing damaged parts (gaskets or corroded plates), ensuring best performances
of the thermal machine at the end of the operation.
Exchanger opening and
cleansing
Plates and gaskets check and control
Addition of new
plates
Closing and pressure test
Strengthening a heat exchanger
requires usually only one working day, with very low machinery and plant
downtime.
Posted in
Water Cooled Condensers .
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