Issue 4/1996

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Direct gas-fired heating and ventilating units with mixing of waste gases and fresh air need low investments and have low operational costs. The paper deals with hygienic problems ari­sing from CO, CO2 and NOx intake to the working and occupational environment. Safe con­centration limits of harmful substances with respect to European standards are given as well as the specification of recommended and non-recommended applications.

The paper deals with merits and drawbacks of copper piping applications. Basic characteristics of copper pipes are given and on their basis the usability of copper piping is discussed.

The paper follows up the prior parts Energy saving in buildings (VVI 3/95) and How to determine the ENCON potential (VVI 2/96) of the series dealing with step by step method in energy audit of buildings.

The study presents data about NOx and CO emissions generated by burning of various fuels in boilers of different capacity, age, technical order; in boilers for heating and for diffe­rent technologies. The results obtained from measurements have a large dispersion. ft is shown that emission Iimits valid in Slovakia are often exceeded there. Although the presen­ted selection of boilers is not entirely representative, the study comes to the right conclusion that the most environmentally friendly way of power and heat generation is gas fuel burning.

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The paper deals with a heat pump which combines advantages of both the sorption and compression systems. The resulting device is smaller than a sorption-based one and has better heating COP than a compression system under equal conditions. Although the Altenkirch cycle was introduced in 1913, the number of devices based on this principle is stilI very low all over the world. The paper describes basic features of the cycle. Attainable values of heating COP for the mentioned heat pump are presented.

Operational conditions of a pump system are investigated with respect to the pump and piping characteristics. Also the start and run-out of engine-pump set adaptively controlled by frequency converter are observed. The adaptive control of operation is demonstrated on the example of cyclic tuming-on of a pump.

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