Need Drain Water Heat Recovery: Different Types Of Heat Exchanger

Posted by LouisWillis on March 11th, 2021

From a didactic point of view, as all drain water heat recovery systems have the same thermal exchange area, it is possible to make a comparison of the thermal and hydraulic performance of each one. In addition, in the suggested experiments it is also proposed to verify the influence of the operating configuration on the heat exchange.

Although the tests proposed here are in steady state, one can easily study the dynamics of the plant in transient tests.

Different Types Of Drain Water Heat Recovery System

Hull and tube:

The heat exchangers of the shell and tube type are very common in the process industries, thanks to its ruggedness, relatively low cost, ease of maintenance and the possibility of building thermal exchange area equipment very high.

In addition, they can also operate under high temperatures and pressures. Such equipment consists of a bundle of tubes surrounded by a hull.

The tubes are welded in the so-called exchanger mirrors, which in turn are in contact with the two heads of the equipment. The flow of fluid in the heater of the exchanger is guided by the baffles, in order to improve the heat exchange and also allow the mechanical support of the tubes.

Double tube:

The double-tube heat exchangers or tubular Bi are similar to the hull and tube exchangers, but instead of having a bundle of tubes inside the hull they have only one tube.

However, as in the case of shell and tube exchangers, double tube exchangers can operate under high pressure and temperature.

This type of exchanger is widely used when the required thermal exchange areas are relatively low, less than 10 m².

Plate changer:

The exchangers plates are ideal for use in food industries and dairy. These exchangers are made up of thin, corrugated metal plates. The hot and cold fluids flow interchangeably, as shown on the left side of Figure 3. This type of exchanger has a large heat exchange area for a relatively small occupied volume.

Technical description: Heat Exchanger

Characteristics

* System consists of three types of heat exchangers, as follows:

* Plate heat exchanger built in 304 stainless steel;

* Tubular heat exchanger built with heads and internal tube in stainless steel 304. External tube in acrylic;

* Hull / tube heat exchanger built with 304 stainless steel heads and inner tubes and outer tube in borosilicate glass;

The system allows students to contact:

* Heat transfer between fluids separated by a wall, in a countercurrent or parallel flow regime;

* Energy balance and thermal transfer efficiency calculation;

* Logarithmic mean temperature concept;

* Concept of global thermal transfer coefficient (u);

* To study the influence of flow and temperature difference on the global heat transfer coefficient; The modes of operation and performance of the three different types of heat exchangers;

Monitoring: Control, recording and indication of parameters:

* The changer plant has control via HMI with a screen of at least 10 inches, ethernet port, vnc functionality;

* Allows you to transport data to an Excel spreadsheet;

* It has heating control;

* It has a temperature, pressure and flow chart;

* It has a temperature, pressure and flow report screen;

* Low level indication of the heating system;

* Figure or image of the changers on the main screen with indication of the parameters;

* License of all software used;

Heating system (hot water):

* Reservoir with a minimum capacity of 4 liters built in stainless steel 304;

* Electric resistance built in stainless steel for easy removal;

* Automatic water feeder through solenoid valve Digital level sensor on / off; Circulation pump suitable for hot water;

* Drain at the bottom to exhaust the system;

Cooling system (cold water)

* Cooling tower calculated to meet water consumption, maintaining a constant temperature at the inlets of the exchangers;

* Circulation pump;

* Drain at the bottom to exhaust the system;

* The heating and cooling system is designed to work with water supplied by the public network, in a closed system;

Control for changing exchanger or flow:

* The control of the choice of the direction of flow, countercurrent or parallel, is carried out manually made by flexible hoses of stainless steel 304 with quick couplings and coated with thermal insulation;

* Selection of the type of changer manually made by flexible hoses of stainless steel 304 with quick couplings and coated with thermal insulation;

* All pipes and connections are made of 304 stainless steel;

* Flow control is done by a stainless steel needle valve;

* Electrical supply: 220 vac - 60 hz;

Finishing:

The components of the heat exchangers must be made of borosilicate glass, 304 stainless steel, teflon and viton;

The structure of the system comprising the heat exchangers, the heating and cooling system, control panel, pipes and accessories, must be:

Built in structured aluminum;

Structure with casters of at least 3 inches with locks.