Dimensional analysis application when calculating heat losses
Abstract
The article describes the procedure for the determination of heat loss through a mathematical model, which was processed through a dimensional analysis. The output of this model is a simple relationship where, based on the locating constant and the regression coefficient, it is possible to determine the loss of the piping system. Subsequently, this method was applied to calculate the heat loss of a pre-insulating pipe buried underground.
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Introduction
Currently, the determination of heat losses is most often achieved through the so-called balancing method, based on the experimental detection of temperature drops into and out of the network. In order to determine the total heat loss of a given section based on the balance method, it is necessary to know the temperature of the heat transfer medium at the beginning and end of the examined section with sufficient precision (at least to two decimal places for short sections) and the instantaneous mass flow rate of the water.
The determination of heat loss through this method is only suitable for very long sections of heat distribution, where the error in measuring the temperature difference does not cause a significant error in the following determination of heat losses. To measure the temperature difference of the heat transfer medium of the short sections, a top measuring technique is required, which cannot be permanently installed in each network, especially when the combined distribution system is several dozen kilometers long.
Conclusion
The newly developed model for determining heat loss does not impose significant demands on the measurement of individual variables, it allows quick results on heat loss, it is reliable and offers some comfort. Putting it into actual practice would, from the point of view of both the manufacturer and the distributor of heat, does not signify any increase in finances and at the same time would make it possible to clearly determine the value of the total or specific heat loss of the network.
This model finds its justification mainly when examining loss on short pipe sections where recording of a drop in water temperature through regular thermometers is impossible or where little accurate information is obtained.