Analysis of the possibilities of optimal connection of heat pumps to the city’s boiler house scheme

Abstract

Relevance: improving energy security, reducing dependence on fossil fuels, and mitigating adverse environmental impacts require the implementation of energy-efficient technologies in district heating systems. For heat sources in Tashkent, reducing dependence on natural gas and heavy fuel oil used as a reserve fuel is an important task. The use of heavy fuel oil is associated with high operating costs and emissions of pollutants into the atmosphere. Aim: to evaluate the effectiveness of integrating heat pumps into the technological scheme of the existing Heat Center No. 3 (HC-3) operated by “Toshkent Issiqlik Markazi” LLC and to determine the optimal connection options for reducing reserve heavy fuel oil consumption and improving the reliability of heat supply. Methods: the study employed analytical and comparative methods, evaluation of the heat pump coefficient of performance (COP), and assessment of the environmental effect. Results: three heat pump connection options were considered: heating makeup water, recovering heat from exhaust flue gases, and connecting the heat pump to the return pipeline of the district heating network. The analysis confirms the technical feasibility and economic viability of applying heat pumps in Tashkent’s district heating system. The integration of heat pumps makes it possible to eliminate heavy fuel oil combustion in the reserve operating mode, reduce operating costs, increase the efficiency of the heat source by 7–10%, and achieve an estimated payback period of 4–6 years. An additional environmental benefit is the elimination of soot and sulfur oxide emissions associated with operation on reserve fuel.

English abstract from the paper. The authors’ abstract, reproduced under CC BY-NC-ND 4.0.

Keywords

• heat pump
• district heating
• boiler house
• ground-source heat pump
• coefficient of performance
• fuel oil
• Tashkent

In plain English

The authors, of Tashkent State Technical University, examine how heat pumps could be built into Heat Centre No. 3 (HC-3) of Toshkent Issiqlik Markazi LLC, which supplies heat to the Shaykhantakhur and Almazar districts of Tashkent. The boiler house burns natural gas, with fuel oil as its reserve fuel. It has two PTVM-50 hot-water boilers of 50 Gcal/h and three PTVM-100 boilers of 100 Gcal/h; two boilers have four fuel-oil burners each, burning 600 kg of fuel oil an hour per burner.

They compare three connections. In the first, a vapour-compression heat pump takes low-grade heat from the return network water or from the ground and warms chemically treated make-up water from 10–15 °C to 35–40 °C; this option has the highest coefficient of performance, 4–5. In the second, lithium bromide absorption heat pumps cool the boiler flue gases from 120–150 °C to 30–40 °C and heat return water from 45–55 °C to 70–80 °C, with a coefficient of transformation of 1.2–2. In the third, heat pumps feed the return pipeline of the heating network ahead of the network pumps and boilers; with return water at 45–70 °C the coefficient of performance is about 2.8–3.5. The scheme drawn for this option has two heat pumps, one air-to-water and one air/water-to-water.

The authors consider a ground-to-water heat pump the most efficient and stable, because the ground stays at +8…+10 °C, while air makes a heat pump ineffective below zero. They estimate that heat pumps would let HC-3 stop burning fuel oil, raise the heat source's efficiency by 7–10%, cut operating costs by more than 50% and pay back in 4–6 years, and that heat from a heat pump in Uzbekistan would cost at least 2–2.5 times less than heat from fuel oil. The boiler house's electrical supply would have to be upgraded.

How to cite

A. R. Ivanisova and M. A. Koroli (2026). Analysis of the possibilities of optimal connection of heat pumps to the city’s boiler house scheme. Energiya va resurs tejash muammolari (Problems of Energy and Sources Saving), No. 3, 2026, pp. 253–261. https://doi.org/10.5281/zenodo.23446898