Efficiency Diagram for District Heating System with Gas Condensing Unit

AbstractThe integration of a flue gas condensing unit in a district heating (DH) system source increases the efficiency of the DH system due to the partial recovery of flue gas heat. A multi-regression equation obtained linking the gas condensing unit efficiency indicator with several statistically significant independent variable parameters based on the statistical analysis of the DH system data in Ludza, Latvia, is discussed in this paper. Parameters related to the interaction between the gas condensing unit and the DH system, boiler capacity and the influence of the DH network return temperature on the efficiency of the gas condensing unit is discussed in more detail. To assess the efficiency of the gas condensing unit and to show the distribution of the boiler house heat load between the boiler and the gas condensing unit during the heating season, a diagram is proposed. As a result of the installation of a gas condensing unit after the boiler, the primary energy savings during the heating season is 11.8%

Analysis of Energy Consumption for Biomass Drying Process

This study is dedicated to the analysis of the drying process energy consumption. In order to evaluate the main energetic processes that consume the most energy, the energy consumption of each individual drying process with and without air recirculation was modelled. The model shows that drying agent (air) recirculation is not an energy-saving operation, since it increases the total electricity and heat consumption. Recirculation of the drying agent increases the moisture content of the drying agent at the dryer entrance, which increases the need for fresh air in the dryer so that it can absorb the evaporating moisture from the dried material. An increased flow of the drying agent in the dryer increases the heat and electricity consumption

Co-Firing of Natural Gas with Wood Dust Experimental Test Runs

Co-Firing biomass in the form of wood dust or sawdust with natural gas is a new concept, which was performed in a specialized burner from the Riga Technical University. In order to test the burner, primary experimental test runs were performed to get an overview of flue gas behaviour. The addition of sawdust increased CO values but O2 values remained very low in the flue gases. This was due to technical problems with the fuel. Co-Firing has the potential to reduce CO2 emissions of energy production and wood dust is an abundant by-product of forestry, therefore the potential has to be explored in future research

Modelling of Technological Solutions to 4th Generation DH Systems

Flue gas evaporation and condensing processes are investigated in a direct contact heat exchanger - condensing unit, which is installed after a furnace. By using equations describing processes of heat and mass transfer, as well as correlation coherences for determining wet gas parameters, a model is formed to create a no-filling, direct contact heat exchanger. Results of heating equipment modelling and experimental research on the gas condensing unit show, that the capacity of the heat exchanger increases, when return temperature of the district heating network decreases. In order to explain these alterations in capacity, the character of the changes in water vapour partial pressure, in the propelling force of mass transfer, in gas and water temperatures and in the determining parameters of heat transfer are used in this article. The positive impact on the direct contact heat exchanger by the decreased district heating (DH) network return temperature shows that introduction of the 4th generation DH system increases the energy efficiency of the heat exchanger. In order to make an assessment, the methodology suggested in the paper can be used in each particular situation

District Heating Systems Performance Analyses. Heat Energy Tariff

The paper addresses an important element of the European energy sector: the evaluation of district heating (DH) system operations from the standpoint of increasing energy efficiency and increasing the use of renewable energy resources. This has been done by developing a new methodology for the evaluation of the heat tariff. The paper presents an algorithm of this methodology, which includes not only a data base and calculation equation systems, but also an integrated multi-criteria analysis module using MADM/MCDM (Multi-Attribute Decision Making / Multi-Criteria Decision Making) based on TOPSIS (Technique for Order Performance by Similarity to Ideal Solution). The results of the multi-criteria analysis are used to set the tariff benchmarks. The evaluation methodology has been tested for Latvian heat tariffs, and the obtained results show that only half of heating companies reach a benchmark value equal to 0.5 for the efficiency closeness to the ideal solution indicator. This means that the proposed evaluation methodology would not only allow companies to determine how they perform with regard to the proposed benchmark, but also to identify their need to restructure so that they may reach the level of a low-carbon business

Empirical Model of Cost Reduction in Local DH Systems. Low Temperature Approach

Improving the efficiency of heating systems can give a tremendous contribution towards the EU energy efficiency target for 2030. Significant heat losses are one of the main disadvantages of the dominating high temperature district heating (DH). Even in summer, the high retention time of water in the network leads to thermal losses from domestic hot water reaching up to about 30 %. An empirical model based on experimental data of heat energy consumption in multi-apartment buildings is created for economical optimization of the operation of DH systems. A methodology has been developed that allows estimating the total energy cost savings (including losses) of buildings associated with the reduction of heat loss in the system, by reducing the supply flow temperature, and increasing electricity consumption by increasing the mass flow rate of water in the network