ERROR IN A SIMPLIFIED CALCULATION OF THE AVERAGE TEMPERATURE OF THE HEAT-TRANSFER AGENT AT THE HEATING PIPELINE SECTION

Abstract

The problem of error estimation for the calculation of the average temperature of the heattransfer
agent on a heating pipeline section as a half-sum of two temperatures of its boundary points
is considered. It is established that in accordance with the physics of the process, the temperature of
the heat transfer agent along the length of the pipe is distributed by an exponential curve. Precise
formulas are obtained both for the mean length of the heat transfer agent temperature region and for
the error in estimating the average temperature from the simplified formula. It is shown that the
simplified formula gives the exact value of the average temperature only if the distribution of the
temperature of the heat transfer agent along the heat pipeline is linear, which is approximately observed
under real conditions. The cases are presented where the error in estimating a simplified formula
is a sufficiently small quantity. It is established that the estimation error depends on the linear
thermal resistance to heat transfer, consumption of a heat transfer agent, its specific thermal capacity
and the length of the heat-pipe section. With the increase in real ranges of the linear thermal resistance
of the heat transfer, the consumption of a heat transfer agent, its specific thermal capacity, the
estimation error decreases, and the temperature distribution along the length of the section approximates
the linear one to a greater extent. On the contrary, with an increase in the length of the section,
the estimation error increases. For selected specific conditions, the dependence of the estimation
error on the consumption of a heat transfer agent and the length of the section has been investigated.
The results of the work can be used in performing thermal and technical calculations of heating
and heat supply systems, as well as pipeline systems.