Thermogram analysis in ZuluGIS using the example of heat network sections in dense urban developments
Author: A.K. Mukhtarov,
Lead engineer at the department of heat network operation
and development at TGC-2 PJSC
TGC-2 PJSC has started using the ZuluThermo Thermogram Analysis software module. The company carried out a preliminary thermal survey of heat network facilities in urban conditions with the aim of:
- determining the location of hidden defects and leaks of the heat-transfer fluid, and eliminating them quickly and effectively;
- conducting a qualitative assessment of trunk mains and district heat networks, ranking the state of heat networks to develop measures for heat supply modernization;
- identifying pipeline sections of heat networks with excessive heat losses;
- adjusting heat network diagrams;
- generating data on the dynamics of changes in the state of heat networks;
- managing and identifying non-contractual heat consumers.
The thermal survey provided us with an orthophoto map, on which each pixel corresponds to radiant temperature on the earth's surface.
Based on the obtained orthophoto map, we did a visual comparison of the heat network map and calibrated the routing of pipelines and utility vaults, which is necessary for the correct representation of heat networks on the diagram and the correlation between pipeline lengths in the database and on location; in addition, this stage serves as the preliminary preparation of thermal survey data for thermogram analysis.
Once the heat network diagrams were aligned with thermograms, we used the Thermogram Analysis module.
Figure 1 Graphical output of the Thermogram Analysis module in color
The output from this module is a ZuluGIS graphics layer organized as a set of lines with the same temperature range (according to a specified palette) connected to a database layer that contains information about the minimum, average, and maximum radiant temperature for each element of a heat network pipeline. These data make it possible to analyze heat network sections and rank the segments of the pipeline sections according to the radiant temperature and heat losses.
Figure 2 The area of the analyzed thermogram in monochrome
As part of this article, we will consider a sample analysis of separate, most indicative, sections of the network.
Figure 3 The diagram of the analyzed area with zones of increased losses
Using RD 153-34.0-20.364-00 Method for Infrared Diagnostics of Telecontrol Equipment (Moscow: ORGRES, 2000), we performed selective calculations of the thermal survey for several pipeline sections of the heat network, 2NB 150, 200 and 250 mm, underground trench installation. Based on the calculated data, as well as the data on maximum and average temperatures on the ground surface above the heat network pipeline section from the Thermogram Analysis module, we conducted an analysis and compiled analytical tables (table 1, table 2) about the condition of heat network sections.
As can be seen from the tables, for section 5, the maximum measured radiant temperature does not exceed the maximum ground surface temperature above the heating main, calculated based on the method above, in normal operation (a standard condition of thermal insulation, dry trench, dry soil around the trench).
Sections 1-3 have a significantly higher maximum measured radiant temperature than the estimated maximum ground surface temperature above the heating main in normal conditions, which may indicate the flooding of the installation site with the service water from the supply pipeline and the dampening of the soil (trench flooding).
Section 4 shows the maximum measured radiant temperature on the ground surface similar to the estimated temperature characteristic of the destruction of the insulation coating in the heat network pipeline section.
It should also be noted that the accuracy of the analyzed data is influenced by the following factors:
- the reliability of data on the method and depth of pipeline installation in the heat network;
- • the availability of information about the flooding of heat network trenches with operational fluids from adjacent utilities (water supply, sewerage).
During a detailed on-site inspection of anomalies detected on the thermogram, in some cases, defects in heating networks were partially not confirmed precisely for the above reasons.
Using the ZuluThermo Thermogram Analysis module makes it possible to get:
- a visualization of thermal radiation on the earth's surface in places where heat network pipelines pass through, in an assigned color palette;
- a representation of heat network zones with maximum heat losses;
- a representation of maximum radiant temperature in a given pipeline section of the heat network;
- an ability to compare the state of heat network pipeline sections with each other and identify areas with increased thermal radiation;
- an ability to rank pipeline sections by the radiant temperature on the surface and the amount of heat loss;
- additional data for technical diagnostics of heat networks.
| Table 1 Control results | ||||||||
|---|---|---|---|---|---|---|---|---|
| Pipeline section number | Location of | Nominal diameter, mm | Maximum/ | Estimated maximum ground surface temperatures above the heating main, °С | Conclusion on the state of the surveyed pipeline section | |||
| the pipeline section | average measured ground surface temperature above the heating main, °С | Normal operation | Lack of thermal insulation | Flooding of the pipe installation site | Flooding of the pipe installation site | |||
| mode | (destruction) | with service water from | with service water from | |||||
| the supply heating main | the supply heating main | |||||||
| and dampening of the soil | ||||||||
| 1 | UV-1 – UV-2 | 250 | 5,37/-4.98 | 1,8 | 3,2 | 5 | 5,9 | Unsatisfactory condition, probable flooding of the trench |
| 2 | UV-2 – UV-3 | 250 | 6,11/-4,22 | 1,8 | 3,2 | 5 | 5,9 | Unsatisfactory condition, probable flooding of the trench |
| 3 | UV-3 – UV-4 | 250 | 19,55/-2,54 | 1,8 | 3,2 | 5 | 5,9 | Unsatisfactory condition, probable flooding of the trench, and dampening of the soil |
| 4 | UV-4 – UV-4a | 150 | 3,66/-1,99 | 1,4 | 2,8 | 4,8 | 5,6 | Unsatisfactory condition, probable destruction of thermal insulation |
| 5 | UV-2 – ext. wall of the building | 200 | 0,144373673 | 1,6 | 3 | 5 | 5,8 | Satisfactory condition |
| Table 2 Measurement log | ||||||||
| Pipeline section number | Location of the pipeline section | Date, time | Water temperature in the supply pipeline of the heat network, °C | Water temperature in the return pipeline of the heat network, °C | Outdoor air temperature, °С | Wind speed, m/s | Maximum ground surface temperatures above the heating main, °С | Note |
| 1 | UV-1 – UV-2 | 23-24.11.2021 | 78; 82 | 47; 49 | -5,7; -7,2 | 3,6; 2,6 | 5,37 | Underground trench |
| 2 | UV-2 – UV-3 | 23-24.11.2021 | 78; 82 | 47; 49 | -5,7; -7,2 | 3,6; 2,6 | 6,11 | Underground trench |
| 3 | UV-3 – UV-4 | 23-24.11.2021 | 78; 82 | 47; 49 | -5,7; -7,2 | 3,6; 2,6 | 19,55 | Underground trench |
| 4 | UV-4 – UV-4a | 23-24.11.2021 | 78; 82 | 47; 49 | -5,7; -7,2 | 3,6; 2,6 | 3,66 | Underground trench |
| 5 | UV-2 – ext. wall of the building | 23-24.11.2021 | 78; 82 | 47; 49 | -5,7; -7,2 | 3,6; 2,6 | -0,68 | Underground trench |
See also: Thermogram analysis