A lighting device, such as for example a LED flexible module, includes an elongated profiled body having a mouth portion, a first and a second lateral sides arranged sidewise of the mouth portion and a web side opposed the mouth portion. The bolt-mounting sink has a cylindrical basin shape with predetermined depth. The working fluid and exhaust fluid may travel through at least a portion of the first heat exchanger in a parallel flow configuration. By using two different kinds of capillary structures to form the capillary structure of the inner wall of the heat pipe, the heat pipe can withstand a heat source of higher temperature, and can also be suitable for a curved pipe.