INVESTIGATION OF THE UNCERTAINTY VALUE AT MEASURING THE TEMPERATURE OF THE COOLANT IN THE PIPELINES WITH OUTSIDE SURFACE MOUNTED TEMPERATURE SENSORS

During performing technological and production processes and monitoring the modes of their operation, the problem of determining the temperature of various media transported through pipelines is solved without incut temperature sensors (TS) in them, i.e. with using outside surface mounted TS (SMTS). This method is allowing to measure mechanical values at technological processes without structure broken and without influence to physicochemical properties of measured media. Using of SMTS possible to register heat losses on sections of heating mains, pollution degree of pipelines internal walls, to control serviceability of measurement channels of temperature of the coolant in heat meters, etc. In the article authors presents results of research the uncertainty values for measuring of the coolant temperature in heating systems pipelines under different modes of its flow. First of all, the uncertainty value of the measurements results was estimated, which was determined by the results of the study for the calculation model and field tests at existing district heating systems. Emphasis is paid on estimating the difference between the registration of temperature in the middle of the pipeline, determined by mortise transducers and the temperature measured by outside surface mounted temperature transducers, taking into account the temperature gradient across the pipeline and the quality of its insulation. It is determined that: the temperature measured by temperature transducers on the surface of the pipeline at different points of its perimeter, with proper installation and sufficient thermal insulation does not depend on their location; the average temperature on the surface of the pipeline, measured using the developed method of installation of PT, slightly differs (ΔT ≈- 0.3⁰C) from the average temperature of the coolant in the middle of the flow; temperature transducers have high reproducibility of measurements and small difference in readings between channels at parallel measurements (»0,03⁰С). It is substantiated that high metrological performances of temperature transducers allow to use them for solving other tasks: measuring the distribution of heat fluxes in heating systems of residential buildings to perform hydraulic balancing of heating systems and increase their efficiency; estimate of contamination of pipelines and heat exchange equipment to determine the need for their washing; determination of thermal resistance of buildings protective structures to assess their energy efficiency; determination of large pumps efficiency by calorimetric method; checking the correct of operation the temperature measuring channels of heat meters and cold meters; in other technology areas where measurements of small temperature differences with high accuracy are required.

Heat flow metering in building practice - A critical field study for a large industrial building complex

Increasingly complex concepts for the heating and cooling supply of buildings require both intelligent and transparent operational management strategies. One way of sequencing and coordinating different generator components is to include information about heat flows on the consumption side. In addition to heat meters, modern pumps also provide heat flow detection. The present study compares the heat flow detection via heat meters and pumps for multiple hydraulic circuits in the operating phase of a large industrial demonstration object. In particular, the influence of typical errors in the installation of the temperature measurement and their elimination are quantified.

Influence of Thermal Retrofitting on Annual Energy Demand for Heating in Multi-Family Buildings

The paper presented the analysis of heat consumption for heating in multi-family residential buildings before and after thermal retrofitting. The analysis involved four groups of buildings, i.e., 43 buildings in total, located in various localities, belonging to one weather station. The predicted level of energy savings resulting from thermal retrofitting was achieved from the energy audits. The actual heat consumption, following the calculation into so-called external standard conditions, was obtained based on the readouts from heat-meters. For each building, the values of heat consumption over the periods of 6–10 years were read. The performance measurements involved the periods before, during, and after thermal retrofitting. The following statistical tests were used for data analysis: Wilcoxon–Mann–Whitney, Shapiro–Wilk, Bartlett, ANOVA, Kruskal–Wallis, Dunn and Holm post-hoc. The performed analyses showed that the mean value of energy savings predicted by audits reached 38.5% when the real mean value of savings, achieved from heat-meters, equaled 30.3%. The annual energy demand factors for heating were calculated for final energy and non-renewable primary energy factors. It was established that most of the analyzed objects fulfilled the primary energy factor requirements found in the Polish technical and construction regulations, which were valid at the time of investment.

Numerical simulation of ultrasonic heat meter by multiphysics coupling finite-element simulation software

Objective: To increase heat calculation accuracy, the numerical simulation of the ultrasonic heat meter is explored by multiphysics coupling. Methods: The COMSOL, a multiphysics coupling finite-element simulation software, is used to build the coupling model of the sound field, structure field, and electric field. The propagation of ultrasonic waves in heat meters is simulated, and its sound field distribution in pure water is analyzed. According to the operating conditions of ultrasonic heat meters, the influence of impurities with different concentrations on ultrasonic propagation is analyzed. The end-face sound pressure levels of the incident transducer and the receiving transducer are compared to obtain the attenuation laws of ultrasonic waves in the liquid-solid two-phase flow. Results: The main lobe and multiple side lobes exist during the propagation of ultrasonic waves. The energy of the main lobe is higher than that of the side lobes. Bubbles resonate under the action of the sound field. Also, bubbles of different diameters correspond to different resonance frequencies, which have larger sound pressure than that of the incident sound field. Most of the sound waves are reflected at the liquid-solid interface, while some of them continue to propagate through the media, affecting the sound pressure distribution on the end-face of the receiving transducer, thereby affecting the measurement accuracy of the ultrasonic heat meter. Conclusion: The reliability and detection efficiency of the heat meter is improved, which is significant and theoretically valuable.

Using Different ML Algorithms and Hyperparameter Optimization to Predict Heat Meters’ Failures

The need to increase the energy efficiency of buildings, as well as the use of local renewable heat sources has caused heat meters to be used not only to calculate the consumed energy, but also for the active management of central heating systems. Increasing the reading frequency and the use of measurement data to control the heating system expands the requirements for the reliability of heat meters. The aim of the research is to analyze a large set of meters in the real network and predict their faults to avoid inaccurate readings, incorrect billing, heating system disruption, and unnecessary maintenance. The reliability analysis of heat meters, based on historical data collected over several years, shows some regularities, which cannot be easily described by physics-based models. The failure rate is almost constant and does depend on the past, but is a non-linear combination of state variables. To predict meters’ failures in the next billing period, three independent machine learning models are implemented and compared with selected metrics, because even the high performance of a single model (87% true positive for neural network) may be insufficient to make a maintenance decision. Additionally, performing hyperparameter optimization boosts the models’ performance by a few percent. Finally, three improved models are used to build an ensemble classifier, which outperforms the individual models. The proposed procedure ensures the high efficiency of fault detection (>95%), while maintaining overfitting at the minimum level. The methodology is universal and can be utilized to study the reliability and predict faults of other types of meters and different objects with the constant failure rate.

Using Different ML Algorithms and Hyperparameter Optimisation to Predict Heat Meters' Failures

The need to increase the energy efficiency of buildings as well as the use of local renewable heat sources has caused that heat meters are used not only to calculate the consumed energy but also for the active management of central heating systems. Increasing the reading frequency and the use of measurement data to control the heating system expands the requirements for the reliability of heat meters. The aim of the research is to analyse a large set of meters in the real network and predict their faults to avoid inaccurate readings, incorrect billing, heating system disruption and unnecessary maintenance. The reliability analysis of heat metres, based on historical data collected over several years, shows some regularities which cannot be easily described by physics-based models. The failure rate is almost constant and does depend on the past but is a non-linear combination of state variables. To predict meters' failures in the next settlement period, three independent machine learning models are implemented and compared with selected metrics because even the high performance of a single model (87\% True Positive for Neural Network) may be insufficient to make a maintenance decision. Additionally, performing hyperparameters optimisation boosts models' performance by a few percent. Finally, three improved models are used to build an ensemble classifier which outperforms the individual models. The proposed procedure ensures the high efficiency of fault detection (>95\%), while maintaining overfitting at the minimum level. The methodology is universal and can be utilised to study the reliability and predict faults of other types of meters and different objects with the constant failure rate.

Development of a Mathematical Model for Precise Temperature Measurement in Geoinformation Systems for Monitoring Individual Heat Consumption In Apartment Buildings

One of the main energy saving objectives is to find methods for metering individual heat consumption in each apartment of an apartment building. Achievements in the area of microprocessor devices made it possible to create a new type of measurement and control systems for monitoring and metering energy resources. Newly developed heat meters are the ground for fundamental changes in energy saving and energy efficiency. Apartment buildings are heated by various hot water distribution systems, for which it is not always possible to use conventional heat meters. The ambiguity related to the parameters of heat meters can adversely affect the estimation of heat consumption by each apartment in an apartment building. This paper is aimed at analyzing a new contact temperature measurement method and means used to create a system for heat monitoring and metering in an apartment building. The developed system can be used to meter energy resources of facilities distributed in a specific area, with geographic referencing to each facility. This makes it possible to remotely monitor heat energy consumption, which makes the energy consumption control system much more transparent and ensures public control. The system gathers data from a large number of users, processes data in real time and promptly responds to users’ requests based on recent developments in information technology. An important advantage of the developed system is that it can be used to anticipate emergency situations taking into account various factors, such as weather conditions and the age of buildings. Due to all of the above, the system can be used in the future not only in Russia but also abroad.