Thermosyphon system - The advantages Thermosyphon system

A simple system, which was used in many early automobiles up to about nineteen forty, is obsolete now. It consists of a radiator connected to the engine through flexible hoses. In this system, the circulation of water is obtained from the difference in densities of the hot and cold regions of cooling water.

The circulating water gets heat from the cylinders of the engine, thereby cooling the same. The same heat in the water is then dissipated into the atmosphere, through the radiator, by mainly conduction and convection. Therefore, the circulating water becomes cold by the time it reaches the collector tank of the radiator.

The same water is then circulated through the engine to collect heat from the cylinders. The rate at which water circulates in this system is proportional to the heat output or the load in the engine and not to the engine speed. Some of the thermosyphon systems also had fans mounted behind the radiator and driven by belts and pulleys from the crankshaft, to assist the flow of cooling air.

The advantages of this system are simplicity and low initial cost. However, because the circulation is maintained only by natural convection, the cooling is rather slow. Further, the radiator header tank must be located higher than the top of the cylinder water jackets. An additional disadvantage is a certain minimum level of water must be maintained in the system.