Compact Heat Exchangers

Heat exchangers are components that transfer heat from a heat source to a heat sink. Both can be a fluid (cooling/heating medium), but often the heat source is a component to be cooled. Compact heat exchangers are required if large amounts of heat per surface area are to be transferred.

Both the powder metallurgically based materials developed at Fraunhofer IFAM Dresden and additive manufacturing processes offer ideal possibilities for the design of efficient compact heat exchangers:

• use of cellular metals for heat exchangers with gaseous media (open cell metals),
• structured evaporator surfaces based on powder metallurgical processes,
• Production of microcoolers or heat pipes through additive manufacturing processes (e.g. cooling of electronic components).

We offer you first-hand service: analysis of heat transportation, thermal simulation and material selection, prototype production of compact heat exchangers and experimental validation in our thermo-technical laboratory.

Open-cell metals such as metal foam, metal fibre or metal wire structures combine numerous properties that are very important for the transfer of large heat flows per unit area in heat exchangers:

• good permeability,
• extremely high volume-related inner surface,
• high thermal conductivity of the base material.

For the selection of suitable materials, the most important fluidic and thermal parameters can be metrologically determined in the thermo-technical laboratory:

• pressure losses during flow - an important parameter for operation,
• heat transfer coefficients related to the contact surface to the heat transfer channel,
• effective thermal conductivity of the cellular structure.

Based on these material properties, tailor-made heat exchangers with high power densities are designed, manufactured and tested as prototypes for special applications. 

High-quality measurement equipment is available for investigating the flow and thermal properties of materials and the performance data of prototype compact heat exchangers:

• various mass flow controllers for air flows or speed adjustable fans,
• air channels with flexible flow cross section for flat and cylindrical and optionally heatable material samples,
• air heaters of various power classes up to 20 kW for compressed air,
• Coriolis measuring/control system for water flows up to 5 litres/min,
• flow channels for water currents.

In addition to the generation of defined air or water flows in variable flow channels, there is also a measuring technology for energy balancing required: sensors for speed, pressure (absolute/relative) and temperature (wall/fluid).