System Integration & Control Systems Design


Managing thermal functions with heat exchangers

February 2021 System Integration & Control Systems Design

When changing a fluid’s thermal state, there has to be a temperature difference between the two mediums for heat transfer to take place, and the heat lost by the hot medium is equal to the amount of heat gained by the cold medium, except for losses to the surroundings.

To continually transfer heat between two mediums, heat exchangers are used. In a direct heat exchanger, both mediums are in direct contact with each other, while in the indirect heat exchanger, both mediums are separated by a wall through which heat is then transferred.

Outside of a heat exchanger, the predominant heat transfer is air, whilst internally it ranges from water, with or without additives, to natural and synthetic refrigerants, steam and even oils. All air-conditioning and refrigeration applications make use of heat exchangers and they extend to other industrial applications such as mining, power generation, military, transport, and agricultural cooling.

To start, when determining the optimal heat exchanger for an application, there are several factors to consider. “Some of the most common include flow rates, maximum pressure inside of the heat exchanger, pressure drop, temperature parameters, system pressures, liquid viscosity and concentration, system upset conditions (start-up/shut down), space availability, expansion plans, life cycle costs and maintenance requirements,” says Zaur Kutelya, business development manager for the Danfoss Heating Team. “Consideration also needs to be given to whether the application will endure continuous or cyclical conditions.”

The various heat exchanger options typically have different operating requirements, as well as preferable refrigerants per application. Each heat exchanger type is therefore designed to perform under particular application criteria.

Heat exchanger sizing is also a function of this application and affects every aspect of a heat exchanger coil. Other crucial considerations not already mentioned include tube sizing, material used, fin spacing and the overall construction methodology.

Further, avoidance of dissimilar metals in the unit removes risks such as galvanic corrosion in applications like marine vessels. Offering a multitude of alternatives allows manufacturers to provide the market with heat exchangers suitable for a wide range of conditions, satisfying all specifications.

Trends

Physical footprint has become a significant trend in recent years as available plant room space becomes smaller. Heat exchangers present themselves in various sizes to minimise the usage of floor space on sites.

Further, market design trends are focusing on the use of synthetic refrigerants, with significant attention being given to low charge systems. In the wider market, the trends have moved towards customers preferring full end-to-end solutions that minimise points of responsibility and localise all project design considerations. This approach means that each individual design decision and implementation is made with cognisance of its impact on the whole project, and therefore the best overall outcomes can be achieved while limiting expenses and errors.

A compact heat exchanger (plate type), depending on the technology and design parameters, is a set of thin heat transfer plates compressed together to form a plate-pack which forms the heat transfer area. Each compact technology has headers and followers which hold the plate packs together. The inner working of a plate heat exchanger is to transfer thermal energy between two fluids, without the fluids mixing.

Plate heat exchangers, now having a wider application use, are also generally smaller and so transportation and installation cost became lower, maintenance is easier, and they are higher in efficiency than the traditional shell and tube system.

For more information contact Lynne McCarthy, Danfoss, +27 11 785 7628, mccarthyl@danfoss.com, www.danfoss.co.za


Credit(s)



Share this article:
Share via emailShare via LinkedInPrint this page

Further reading:

TwinCAT for test rig automation
Beckhoff Automation System Integration & Control Systems Design
Flexibility and high performance in control program generation for endurance testing.

Read more...
ABB moves toward zero-carbon mines
ABB South Africa System Integration & Control Systems Design
ABB has launched ABB Ability eMine, a portfolio of solutions that will help accelerate the move toward a zero-carbon mine.

Read more...
Legacy alarm upgrade for Uganda’s power generator
Omniflex Remote Monitoring Specialists System Integration & Control Systems Design
In a digital age, where we rely so heavily on computer-based equipment, do we still need bulky, hard-wired annunciator panels?

Read more...
EtherCAT saves space in wind turbines
Beckhoff Automation System Integration & Control Systems Design
At this year’s Husum Wind during September, Beckhoff demonstrated its many years of know-how and its broad product range for the wind power industry.

Read more...
Smart production line configuration
Iritron System Integration & Control Systems Design
In the discrete manufacturing environment, a tool change or the reconfiguration of a production line is a major cause of production loss.

Read more...
Migration from factory automation to process engineering
Pepperl+Fuchs System Integration & Control Systems Design
Pepperl+Fuchs has developed a range of high-tech sensors that have proven themselves in discrete applications. With added explosion protection, they are also suitable for process engineering in zones 1/21 and 2/22.

Read more...
Totally Integrated Automation – added value in three dimensions
Siemens Digital Industries Editor's Choice System Integration & Control Systems Design
Discover everything that’s in TIA, the leading automation concept from Siemens, and how it all works together to create a unique product for machine builders and industrial enterprises.

Read more...
Smart water system management
Saryx Engineering Group System Integration & Control Systems Design
The Saryx Engineering Group is leveraging digital technologies to manage water storage, flow, usage and treatment more efficiently.

Read more...
The brewery of the future
Siemens Digital Industries Process Dynamics System Integration & Control Systems Design
Meeting current and future customer requirements quickly and with the highest quality is key to the food and beverage industry.

Read more...
Danfoss completes acquisition of Eaton’s hydraulics business
Danfoss News
Danfoss has officially finalised its US$3,3 billion acquisition of Eaton’s hydraulics business, following confirmation of all necessary regulatory approvals and closing conditions.

Read more...