The LHP principle also provides great scope for various design embodiments. This refers, first of all, to the design of the evaporator and the condenser, and also to the variants of their joining.

The main form of the evaporator is cylindrical with a diameter from 5 mm to 30 mm and more. The length of its active zone (heating zone) depending on the diameter may range from 20 to 400 mm. The compensation chamber may be located in the same body as the evaporator or separately. If the dimensions of the heat-load source are sufficiently large, an LHP may contain several parallel evaporators joined by a common thermal interface.

The shape, dimensions and design of the condenser — heat exchanger may differ greatly depending on the conditions of heat exchange with the heat receiver. Fig. 4 presents the main types of condensers used in LHPs.

Since the evaporator and the condenser are joined by means of separate pipe-lines of a relatively small diameter, which contain no capillary structure, they can bend quite easily and take practically any configuration if necessary.

Fig. 5 gives as an example the external view of an experimental LHP, whose pipe-lines 6-8 mm in diameter and about 21 m in length are bent in the form of a flat coil. The device is equipped with a cylindrical evaporator 24 mm in diameter with an active zone length of 190 mm and a condenser 300 mm long made by the variant “d”. The maximum capacity demonstrated by the LHP with ammonia as a working fluid when operated in a horizontal position was 1.7 KW at a vapor temperature of 60oC. The total thermal resistance in this case did not exceed 0.04 K/W. Another example characterizing the potentialities of these devices is an ammonia LHP 4.5 m “high” with pipe-lines 6 mm in diameter, which on trials transferred downwards a heat flow of 1 KW at the same vapor operating temperature. The tests and calculations performed show that the indicated technical data are far from being limiting for devices of such a type even with ammonia as a working fluid. With the use of water at an operating temperature of 100-150°C the heat-transfer distance and its value may be considerably increased.