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.
Further reading:
The time is now for systems integrators
Editor's Choice System Integration & Control Systems Design
Integrators combine sophistication regarding technology innovation with practical, hands-on experience. Collaborating with systems integrators is the means to significant productivity improvement, powered by the convergence of automation and information and operations technology.
Read more...
System integrators are a diverse market
Editor's Choice System Integration & Control Systems Design
System integrators (SIs) combine expertise on emergent technologies with real world experience. Working with SIs, it’s inevitable that at some point someone will say, “We’re not a typical SI.” And in many ways, it’s true. SIs come in all shapes and sizes.
Read more...
Avoiding the pitfalls of PLC and scada control system integration
Iritron
System Integration & Control Systems Design
Upgrading your control system by integrating PLCs with scada systems should be a simple seamless process. Regrettably, the industry is plagued with control system integration and upgrade myths and misconceptions that can lead to liability issues, project delays, cost overruns and decreased plant performance.
Read more...
EtherCAT measurement terminals for vehicle development at Mercedes-Benz
Beckhoff Automation
System Integration & Control Systems Design
At the Mercedes Technology Centre plant in Sindelfingen, Germany, car axles are examined with the highest precision on four test benches, in parallel with road tests and simulations. All data is acquired using PC-based control from Beckhoff.
Read more...
Loop signature 23: Tuning Part 2.
Editor's Choice System Integration & Control Systems Design
It is my opinion that most tuning methods are very crude. They do of course also offer a starting point for tuning if one is not fortunate enough to have a sophisticated tuning package like a Protuner around.
Read more...
PIC microcontrollers with integrated FPGA features in TME
System Integration & Control Systems Design
The new PIC16F131xx microcontrollers in TME’s offering from Microchip are ideal for the evolving and miniaturising electronic equipment market, offering efficient power management and predictable response times for controllers.
Read more...
Five smart machine trends you need to know
Adroit Technologies
System Integration & Control Systems Design
The last ten years have brought about dramatic advances in technologies that OEMs had never realised would affect their designs or the saleability of their machines, much less impact business models and profits so dramatically. The following discussion will cover key advancements and recommendations all OEMs should be adopting in their design processes to stay current and competitive.
Read more...
36 years of innovation and success
SAM Systems Automation & Management
Editor's Choice System Integration & Control Systems Design
Systems Automation & Management was established in 1988 at a time when there were no other systems integrators (SIs) in the process business.
SA Instrumentation & Control’s editor caught up with managing director, Claudio Agostinetto to find out more about how this thriving company has prospered over the last 36 years.
Read more...
Understanding the role of AI in generative engineering design
System Integration & Control Systems Design
When a design engineer sets out to design a new part, component, or assembly, the intent is to meet the design requirements for fit, form and function, and also incorporate a certain degree of innovation and elegance to the overall design. There is no reason to re-invent the wheel by introducing a new design.
Read more...
PCS stays up so you don’t have to
PCS Global
System Integration & Control Systems Design
Maybe it’s time to look at a solution that stays online 99,99999% of the time so you don’t have to. This the world of Stratus computer platforms, tailor-made for your critical applications.
Read more...
printer friendly version