Thermal cooling in the luminaire housing

There are very high hygiene require­ments in oper­at­ing rooms. Not only for per­son­nel or ven­ti­la­tion and air con­di­tion­ing. They also apply to the equip­ment used there. Oper­at­ing room lumi­naires, for exam­ple, have to meet strict spec­i­fi­ca­tions. Under these spe­cial con­di­tions, Merkle & Part­ner devel­oped an inter­nal cool­ing con­cept for an OR LED lumi­naire togeth­er with a lumi­naire man­u­fac­tur­er on the basis of a flow-ori­ent­ed sim­u­la­tion calculation.

In prin­ci­ple, it would be a sim­ple mat­ter to give a prod­uct such as a lumi­naire more sur­face area in order to increase heat exchange with the envi­ron­ment. How­ev­er, ribbed sur­faces, for exam­ple, are not allowed on lumi­naires used in oper­at­ing rooms because, among oth­er things, uncon­trol­lable dust for­ma­tion must be avoid­ed. The pure, smooth stain­less steel sur­faces of the lumi­naire must also not emit heat or gen­er­ate air cur­rents to the out­side. Since the dimen­sions of the lumi­naire body can­not be over­sized either, a new solu­tion had to be found for an inter­nal cool­ing con­cept; based on sim­u­la­tion using com­pu­ta­tion­al flu­id dynamics.

Here, the lumi­naire includ­ing all com­po­nents as well as their prop­er­ties are mapped in a sim­u­la­tion in order to work out a sen­si­ble cool­ing con­cept. Not only is the air cir­cu­la­tion inside the lumi­naire visu­al­ized real­is­ti­cal­ly, but tem­per­a­ture dif­fer­ences and changes with chang­ing geome­tries or ven­ti­la­tion rates are also reproduced.

To ensure that the air is not only moved but also direct­ed to the heat sources in a tar­get­ed man­ner, the nec­es­sary geom­e­try of the lumi­naire’s inter­nal struc­ture was opti­mized by means of a flow cal­cu­la­tion. The place­ment of com­po­nents for opti­mal heat dis­tri­b­u­tion with­in the lumi­naire was also opti­mal­ly designed. The sur­gi­cal lumi­naire thus offers an inter­nal cool­ing con­cept that is so well designed that the lumi­naire meets all the require­ments for use in the oper­at­ing room.

“Eco­nom­i­cal­ly, in terms of time, but also func­tion­al­ly, the design using com­pu­ta­tion­al flu­id dynam­ics (CFD) offers the opti­mal solu­tion. Dig­i­tal test mod­els can be used to iden­ti­fy sen­si­ble, but also less sen­si­ble, paths at an ear­ly stage and to devel­op inno­v­a­tive cool­ing con­cepts. It is no longer just a ques­tion of the time sav­ings offered by sim­u­la­tion cal­cu­la­tions. Rather, dig­i­tal con­cepts can be devel­oped that per­haps would not have been dis­cov­ered via real trials.”

- Ste­fan Merkle, Man­ag­ing Direc­tor of Merkle & Part­ner GbR