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Small, compact, powerful: VX plate heat exchangers from GEA PHE Systems cool the new yacht engine generation from MAN

More power with simultaneous weight minimisation - that is the formula for success of the new V12 yacht engine, the most powerful unit in the MAN range of ship engine design. With a consistent programme of weight reduction measures the engineers of this traditional Nuremberg-based company have achieved a top rating of 1.78 kg per kW. The 1325 kW diesel engine is cooled by a modified VX plate heat exchanger (PHE) from GEA PHE Systems. The gasketed seawater cooler is a component in the closed cooling circuit, fixed firmly to the engine, which meant that it also had to undergo weight optimisation.

Only titanium plates guarantee corrosion protection on the high seas

The VX plate heat exchanger is installed on the front side of the engine block directly in front of the expansion tank of the fresh water circuit. The cooling water flows through the cylinder heads, charge air cooler and oil cooler at an operating pressure of around 4 bars. Here the fresh water takes up the complete waste heat from the engine and transfers it to the seawater in the PHE in counterflow. As the salt concentration of the seawater would quickly damage stainless steel grades, GEA PHE Systems always uses titanium plates in seawater coolers. Only this high-quality material guarantees the necessary corrosion protection and ensures process reliability on the ocean waves.

VX plate pressed in titanium for the first time
And this was the challenge faced by the GEA engineers this time. Up until now the VX plate had never been pressed in titanium. For a good three months at the Canadian subsidiary GEA ViEX they worked on how to achieve the required weight reduction of the VX plate without losing any of the pressure resistance as the second elementary parameter.

As the raw material titanium cannot be easily deformed, it was necessary to optimise the pressing process. This was successfully achieved by specific modifications to the pressing tool.

Reduced plate thickness with simultaneous increase in heat transfer

Up until now plate thicknesses of a minimum of 0.5 mm had been the lower limit, but now the engineers achieved a VX plate thickness of 0.4 mm and at the same time it was also possible to increase the heat transfer rate by a good 4%, representing a further optimisation of the engine cooling performance. The new MAN V12 unit has a cooling performance of 1060 kW, dissipated via 42 VX plates. VX-13 plates are fitted in the plate pack as their dimensions fit ideally to the engine geometry. The heat transfer surface per plate is 0.13 m². NBR is used as the gasket material.

A further challenge for the GEA engineers was the transverse installation of the seawater cooler required by MAN, because standard VX plates have parallel flow. A simple rotation through 90°C to achieve vertical installation couldn’t be the answer if emptying and venting the unit was also to be possible.

New gasket allows diagonal flow of the plates

The solution here was a special gasket that meant that the flow across the plates could be deflected diagonally without much trouble. Only a new gasket tool was necessary as GEA ViEX hadn’t previously had a corresponding gasket for diagonal flow.

VX plate heat exchangers cool high-performance V12 yacht engine

The MAN V12 with two-stage turbocharger and 1325 kW was launched at the end of last year and is currently the top-of-the-range model from this traditional Nuremberg-based company. The completely new engine range, specially tailored for maritime applications, comprises four models, two V8 and two V12 models, each available with single-stage and two-stage charging, and all of which are cooled using a VX plate heat exchanger from GEA PHE Systems.

As a result of a company-wide restructuring process in 2001 MAN set up a separate business sector “Engines”, based at the main Nuremberg facility. Here the engine specialists produce diesel and gas engines, of which 85 % are installed in commercial vehicles. In the past small series of engines were modified for maritime applications.

Optimum combustion process with exemplary emission values

With its series based around the new V12 yacht engine for the very first time MAN is presenting high-performance models specially designed for pleasure craft and motor yachts, with the special feature being the bedplate concept. The bedplate replaces the individual crankshaft main bearing caps and makes a considerable contribution to the rigidity of the crankcase and to minimizing sound radiation. The result of the combination of second-generation common rail injection and an optimally designed combustion process is high performance combined with exemplary emission levels.

Info:
The MAN V12 yacht engine is the top-of-the-range model from this traditional Nuremberg-based  company. The high-performance units are cooled using VX plate heat exchangers from GEA PHE Systems. In order to meet the customer’s product specifications the VX plate was pressed using titanium for the first time and fitted with a newly developed gasket to enable diagonal flow.