Energy balance of automotive thermoelectric cup holder

Design and optimization of a thermoelectric cooling and heating system for a cup holder between dash board and center arm res of a passenger vehicle.

Customer Requirements

The task was to design and optimise a thermoelectric cooling and heating system for a cup holder between dash board and center arm rest of a passenger vehicle. Given constraints were a very limited space, power consumption for thermoelectric module and fan as well as the noise level of the fan.

In the initial design a peltier cooler reached a beverage temperature of 9°C at an ambient temperature of 22°C and drew a current of 4A. Analysis showed that not even 15% of the cooling capacity was used to effectively cool the beverage and the remainder was lost to the ambient and as back flow to an overheated heat sink. The overall energy balance revealed the low efficiency of the initial system.  

The analysis was performed using a thermal design software with an integrated detailed model of the thermoelectric module with its geometry factor, number of couples and material properties Seebeck-coefficient, resistivity and conductivity as a function of temperature. The final design was capable of cooling the beverage down to 2°C. More than 40% of the cooling capacity of the thermoelectric module was used to cool the beverage. At the same time the power consumption was reduced by approximately 25%. The design changes were made in the insulation geometry and properties, heat sink profile, air ducts and selection of a lower current thermoelectric module.

The final design achieved the best performance among several competing suppliers in an automotive contest. The methodology of analysing heat flows and energy balance was key in determining the base concept and components. Since start of production in 2008 many ten thousands of thermo cup holders have been installed.

Thermal simulation of thermoelectrically cooled cup holder. The vicinity of hot and cold areas indicate the need of good insulation.

A successful example of this is the thermal cup-holder, a high-tech product in the Audi Q5. The tempered cup-holder can keep both hot or cold temperatures. At the press of a button the temperature of the thermal-insert can be set between +3° and +53° Celsius. That the Weber experts scored an enormous success with the demanding implementation of this thermal cup-holder is also verified by the fact at in December 2006, they were awarded first prize in the Audi Concept Competition.

“The expertise of AMS Technologies in the thermal and thermo electrical design helped us winning the Automotive Challenge "Thermal Cup holder.” The Weber Group produces and develops plastics components, modules, systems and injection moulds. By choosing AMS Technologies we have found a partner who can provide a turnkey solution from design expertise to custom Peltier element components." Klaus Kinner, Competence Center Purchase, www.weber-dillenburg.de

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