Ladislav Šnajdárek

AUTOMATIC BIOMASS BOILER WITH AN EXTERNAL THERMOELECTRIC GENERATOR

This paper presents the design and test results of an external thermoelectric generator that utilizes the waste heat from a small-scale domestic biomass boiler with nominal rated heat output of 25 kW. The low-temperature Bi2Te3 generator based on thermoelectric modules has the potential to recover waste heat from gas combustion products as effective energy. The small-scale generator is constructed from independent segments. Measurements have shown that up to 11 W of electricity can be generated by one segment. Higher output power can be achieved by linking thermoelectric segments. The maximum output power is given by the dew point of the flue gas. The electrical energy that is generated can be used, e.g., for power supply or for charging batteries. In the near future, thermoelectric generators could completely eliminate the dependence an automated domestic boiler system on the power supply from the electricity grid, and could ensure comfortable operation in the event of an unexpected power grid failure.

Heat Exchangers for Condensation and Evaporation Applications Operating in a Low Pressure Atmosphere

This paper presents a state-of-the-art study of a heat transfer process in liquid spraying heat exchangers placed in a vacuum chamber. The experimental case studied here describes the behavior of a falling film evaporation and condensation mode on horizontal tube bundles. The study aims to obtain the heat transfer coefficient and its correlations by means of a mathematical model.

Influence of the Surface Treatment of Tubes on the Heat Transfer in Low Pressure Atmosphere

This paper presents the current research on heat transfer at a sprinkled tube bundle consisting of smooth tubes and located in a chamber inside of which a low pressure is created by a liquid vacuum pump. It also monitors the changes of the heat transfer coefficient in relation to the speed of sprinkled and sprinkling liquid flow, thermal gradient.