Case Study: Efficient Chocolate Cooling with Hexonic Shell & Tube Heat Exchangers

Sector: Food Industry – Chocolate Manufacturing

Challenge

Raptronic Process Engineering, one of the leading Romanian companies specializing in chocolate production systems, faced a critical challenge in designing a cooling process for liquid chocolate.
The chocolate needed to be cooled efficiently from 68°C to approximately 45°C, using water at 41°C as the cooling medium.

However, the process posed several technical difficulties:

Lack of clear specifications for the working fluid — no reliable data for viscosity and density variations in the temperature range.

High risk of chocolate crystallization during cooling, especially at the tube surface.

The non-Newtonian behavior and high viscosity of chocolate required precise calculations to ensure optimal shear rates.

The system had to be insulated while meeting a strict delivery deadline.

Solution

After extensive simulations and parameter adjustments, the engineering team selected two Hexonic DNA 508.10.S610 FS.PRO.SS shell & tube heat exchangers installed in series.
This configuration provided a total heat load of 231 kW with a Log Mean Temperature Difference (LMTD) of 10.6°C.

Key design adaptations included:

Product flow on the shell side for optimal handling of high-viscosity chocolate.

Horizontal installation to ensure complete drainage.

Extended flange necks by 60 mm to allow space for thermal insulation.

Adjusted pump power to manage a total pressure drop of 175 kPa on the chocolate side.

The engineering approach combined practical experience with non-Newtonian fluids and precision modeling, allowing the use of a “conventional-type” shell & tube exchanger in an application where such designs are typically avoided.

Results

Despite the challenges, the implemented solution met all performance and quality expectations.
The innovative use of Hexonic DNA exchangers allowed Raptronic to:

Achieve efficient and stable cooling without chocolate crystallization.

Maintain high product quality and process reliability.

Deliver the project on time, despite the need for custom modifications.

This project demonstrated that with advanced design and engineering expertise, shell & tube heat exchangers can be effectively applied even in demanding food industry applications, such as chocolate processing.

About the Product

Hexonic DNA Series – Industrial shell & tube heat exchangers designed for high efficiency and versatility.
Their unique tube bundle architecture ensures excellent heat transfer even with challenging media, making them suitable for applications in HVAC, food processing, and chemical industries.