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Solving a Thermal-Mechanical Problem in Hydroforming L-Foot Fins for Heat Exchanger Tubes Using Finite Element Analysis

February 28, 2023

Heat exchangers and condensers are an essential component in many industries, such as chemical, power generation, and refrigeration. They transfer heat between two fluids, which can be gases or liquids, without them coming into contact with each other. Heat exchangers are designed to maximize heat transfer efficiency while minimizing the size, weight, and cost of the equipment.

In this article, we will discuss how we used finite element analysis (FEA) to solve a thermal-mechanical problem in hydroforming L-foot fins for heat exchanger tubes. We will also highlight how we leverage our expertise in thermal design and HTRI to achieve optimal contact between the fins and tubes.

Figure 1. Finite element hydroforming SDEA

Problem Description:

The client approached us with a challenge in the hydroforming of L-foot fins for their heat exchanger tubes. The L-foot fins are used to increase the surface area of the tubes, which in turn increases the heat transfer rate. However, during the hydroforming process, the tubes tends to burst due overpressure or if underpressurized l-foot will not bend and guaranteed good thermal contact.

Subtle balance between applied forming pressure, l-foot bend and spring back reallocation can make the process challenging. Numerical modelling can help to predict manufacture parameters and minimize production stage issues.

Our client wanted us to solve this problem while maintaining optimal contact between the fins and tubes to ensure the heat exchanger’s efficiency. We decided to use FEA to model the thermal-mechanical behaviour of the fins during the hydroforming process.


We used a non-linear elastoplastic material model for the L-foot fin, which considers the material’s non-linear stress-strain behavior. Material flow due yielding and spring back balance needs to critically capture to ensure accuracy in the results.

Because we use HTRI to thermal dimensioning the condensation vessel, its mandatory to ensure assumptions realistic and thermal contact is a key parameter defining the energy exchange area.   We assumed that the optimal contact between the fins and tubes was achieved, which is a standard assumption in heat exchanger design. Dangerous assumption if we discover on operation that is not real.

We performed a series of simulations with varying process parameters to identify the optimal hydroforming conditions. We looked at the effect of changing the hydraulic pressure, tube diameter, fin thickness, and fin length on the hydroforming process.

Figure 2. Aluminium condenser HTRI SDEA


Our simulations showed that the optimal hydroforming conditions were achieved with a hydraulic pressure of 450 bars, a tube diameter of 20mm , a fin thickness of 2 mm. We were able to achieve optimal contact between the fins and tubes while maintaining the L-foot fin’s structural integrity.


In conclusion, we were able to solve the thermal-mechanical problem of hydroforming L-foot fins for heat exchanger tubes using advanced tools. We leveraged our expertise in thermal design and HTRI to achieve optimal and adjust the equipment size down to a optimized solutions ensuring will performance targets will be achieved during the whole life of vessel. Our non-linear elastoplastic FEA model was critical in accurately predicting the behaviour of the L-foot fins during the hydroforming process.

At SDEA, we specialize in thermal design and analysis using state-of-the-art tools like HTRI and FEA. We can help you design and optimize your heat exchangers to maximize efficiency and minimize costs. Contact us today to learn more about our services.

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