What makes Bronswerk Heat Transfer’s Subsea Cooler unique?

16 min read - published on June 16, 2021

Over the years, Bronswerk Heat Transfer BV has developed multiple products which have had significant impact on wider industry; such examples include industrial heat pumps, the Reactor Effluent Air Cooler Solid Block Header, and the Subsea Cooler. In this article, Johan van der Kamp, a lead engineer in the development of Bronswerk’s Subsea Cooler, explains why this product was one of the company’s most impactful achievements. 

Innovative Subsea Coolers

Bronswerk Heat Transfer produces bespoke solutions, nothing they do can be considered ‘off the shelf’, and the Subsea Cooler is no exception to that. The team’s skill set spans design, service, improvement of existing equipment, production, and maintenance and they are active in a vast range of industries, such as oil & gas, power, chemical, food, and pulp & paper. The proclivity of the company’s work is underscored by a constant drive for innovation and quality customer service, the latter of which is maintained long after the initial solution is completed.

“First things first, there are very few Subsea Coolers”, Johan begins. “We at Bronswerk were, I believe, the very first to produce one and this means that when people think of Subsea Coolers, they automatically think of us. This product is really evidence of Bronswerk’s innovation as a company”. 

Bronswerk innovation solves the problem 

In 2019, Bronswerk was approached by a gas company to design an efficient and cost-effective solution to their issues of cooling and compressing gas in a remote location. The initial problem was that the gas company needed to install some form of compressor on its offshore platform, but it lacked the space and its limited electrical supply meant that there was little to spare for cooling equipment. Certain options had already been ruled out, such as building a pipeline from the platform to the shore – this would have been costly as uncompressed gas is highly corrosive and the pipe would need to be constructed entirely of super duplex material to prevent rapid corrosion.  

In line with the company’s strengths in innovative solutions, the Bronswerk team knew they needed to develop a product which could withstand challenging conditions, required little to no maintenance, and saved valuable space. 

The trouble with traditional methods

Before exploring the advantages of Bronswerk’s Subsea Cooler, it is important to acknowledge the methods for which this system provides an alternative. Traditional methods of cooling on offshore platforms include using ambient air and sea water, however neither of these are ideal solutions. For cooling gas with ambient air, Johan explains that there are multiple disadvantages: “Air-cooled coolers require a lot of space, which is problematic on a platform. Furthermore, they require e-power for the fans that blow the air through the cooler bundle. A last point to mention is that the cooling air is very saline, and therefore aggressive, which requires special attention.”

For cooling with seawater, pumps are required in order to transport seawater to the platform. “Pumps are very prone to failure and need maintenance. This method also requires special materials, not only for the pumps, but for all equipment in contact with it. That’s why normally a seawater circuit is designed with a heat exchanger. In the heat exchanger the seawater takes the heat from a closed-circuit cooling water loop on the platform.”

Neither of these methods are optimal for remote locations such as offshore gas and oil platforms, which are often unmanned. The moving parts of a seawater pump regularly need maintenance and repair, and lead times for new parts are slow when the platform is so remote, and the air cooler is too space invasive. 

Low mechanics, low maintenance

The Bronswerk team developed the Subsea Cooler as a smarter and more efficient method of cooling. By placing the equipment in the water beneath the platform, they knew they would be saving space. But the product is even smarter than that; the seawater surrounding the cooler is heated and thus creates a natural draft in the sea as an engine for cooling. Moving with the waves and using the kinetic flow of the ocean in order to generate its own power means that there are no pumps or rotary parts involved. With the mechanics of the system kept to a minimum, maintenance is hardly necessary. 

A further challenge was the thermal design for the cooler. Johan explains: “Together with the customer, we came up with a mechanical design specially for the frame; on top of the cooler there is a strong wire mesh cage which ensures that pieces of equipment that fall into the water don’t destroy the pipes because piping which contains high pressure gas shouldn’t leak - it causes big problems.” 

Listening to each of the gas company’s concerns and addressing them specifically, as a custom solution, led to a robust product optimized for its surroundings. 

“This way of working really fits with us at Bronswerk,” says Johan. “We start the project from the beginning and use all of our expertise to find something new together with the customer. It is always possible to make equipment that is constantly the same, but we like to do new things and we always cooperate closely with the customer in those cases”.  

With a 100% saving on plot space and an impressive 25% saving on cost, thanks to its ergonomic design, the Bronswerk Subsea Cooler is a tailor-made solution combatting multiple issues.


Bio-fouling remains one issue that Bronswerk cannot solve conclusively, but the team ensures close monitoring in an aftercare service. Bio-fouling is a universal issue for all subsea equipment. It refers to the degradation caused by marine life and micro-organisms as they accumulate on equipment, and can mean that parts are damaged or simply inaccessible. Fortunately, due to the ‘no-moving-parts’ aspect of the Bronswerk Subsea Cooler, this risk is reduced and replacement of expensive pumps and valves is not necessary.

Bronswerk’s customized approach does not end with product design, build, and placement. Each aftercare service is dependent on where in the world the Subsea Cooler is located and the depth of the equipment. The team offers a project-specific solution here as well. 

“We give a few solutions to the customer on how to cope with fouling. We think along with them and make our design around the option they choose,” Johan says. One option is to use a small, unmanned submarine which dives down to clean the Subsea Cooler with a high-pressure water flow. Alternatively, the equipment can be lifted back up to the deck for cleaning. Or there is the option of using divers. Once again, Johan implies that this is simply ‘the Bronswerk Way’: “Cleaning away biofouling is not easy underwater, but it is an important part of our service. Fouling can be monitored and predicted, so cleaning can be scheduled”. 

The key advantages of the Subsea Cooler

  • 100% space-saving solution
  • Generates its own power through the kinetic energy of its subsea environment
  • No rotary parts, reducing risk of failure or repair; it is a low maintenance system
  • Bronswerk provides a bespoke solution, even in cleaning 
  • Consultation through to installation and aftercare are a collaborative effort between Bronswerk and the customer

Worldwide high quality

Bronswerk Heat Transfer has been developing custom solutions for a variety of industries since 1940. Although headquartered in Nijkerk, the Netherlands, Bronswerk prides itself on being able to work to the same high standards anywhere in the world thanks to its trusted partners who uphold the same quality processes. Their team of 110 employees combines high skill level with a passion for innovation and a keen awareness of customer involvement. From this, Bronswerk Heat Transfer is regularly able to produce high quality and bespoke heat exchange solutions such as the Subsea Cooler.

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