Research of Technological Possibilities of Heat Pumps’ Application in District Heating of Residential Buildings

Abstract

The main users of district heating (DH) systems are multi-apartment buildings – 53% of these buildings in Lithuania are supplied with heat from DH systems. Heating systems in buildings are the largest final consumer of energy, accounting for almost half of total energy consumption in many European countries. One of the measures planned for the Lithuanian energy policy in the heat sector of renewable energy sources (RES) until 2030 is the installation of heat pumps (HP) in the DH networks. The purpose of the study is to evaluate the technological possibilities of integrating HP into existing buildings to evaluate the low temperature heat supply. To evaluate the potential temperature lowering of the building heating system, a graph of the lowest possible building heating system temperatures is set, according to which the heat pump for the heating substation is selected, which would raise the temperature of the heat carrier supplied from DH networks to the required temperature for the heating and hot water systems of the building. Applying thermodynamic analysis, a mathematical model is developed that evaluates the ability of the HP to raise the temperature of the supplied heat carrier at the heat substation and determines the energy efficiency of such a solution. During the simulation, two alternatives of constant (regardless of outdoor air temperature) heat carrier temperatures supplied from DH networks were considered: 60 °C (alternative A) and 55 °C (alternative B). To adapt the most appropriate option for the integration of HP, it would be appropriate to combine both alternatives, i. y. to supply 60 °C from the DH network in the cold period of the year and 55 °C in the warm period of the year.

Towards Climate Management of District Heating Enterprises’ Innovative Resources

“…At the same time, the sustainability of the functioning of district heating enterprises directly depends on the level of provision with primary resources necessary for heat production. In this context, innovative solutions in the district heating system are the following: diversification of renewable sources of resource supply in the district heating system using a geographic information system (GIS) [10]; cogeneration and trigeneration; use of biomass for the production of solid biofuels [11,12]; transition to low-temperature district heating and high-temperature district cooling [13,14]; use of geothermal energy [15]; ensuring the optimal distribution of thermal resources in a spatially distributed network and the creation of carbon-neutral energy systems [16]; integration of solar thermal panels into district heating plants [17]; installation of heat pumps [18]; and accounting for the specifics of the production, supply, use and climate management of green electricity and heat [19][20][21][22]. One of the measures planned by the Lithuanian energy policy for the heat sector of renewable energy sources, is the installation of heat pumps in district heating networks by 2030 [18].…”