Thermodynamic modeling of a fourth generation disctrict heating system in Brazil

Abstract

Heating and cooling is accounted for about half of the global energy use where domestic heating is the main part of this energy consumption. Due to the importance of heating in the global energy crisis, district heating systems are on the verge of a transition to their fourth generation from in-operation third generation. In a fourth generation district heating system, the penetration of renewables is supposed to be much higher (up to 100%), there is strong synergy between the energy sectors, the rate of losses are considerably lower and the whole system is remarkably more energy efficient. In spite of the extensive advancement made in district heating systems, this technology has not been practically introduced to the Brazilian energy system yet. The main reasons for this are the low demand of space heating in the country due to the moderate to hot climate, and the highly renewablebased electricity sector of the country that it has made the use of electricity for heating application rational. In this project a district heating system, based on the latest standards of the fourth generation will be designed, sized and modeled for a residential region in the south of Brazil. The main objective of the project is to evaluate the technical feasibility of the implementation of such advanced district heating systems in the future energy matrix of Brazil. For this, various possible district heating technologies that are compatible with the 4GDH concept will be investigated and an innovative solution will be proposed. The performance of these systems will be comprehensively compared in terms of heat losses, the pipeline sizing, the pump work, and etc. Therefore, a through technical comparision of the existing generation of district heating, so-called the 3rd generation of district heating, ultra-low temperature system and proposed non-uniform temperature system will be done. The results show that the energy system of the case study area can effectively host a district heating system. The considered cases include the third generation, the low-temperature and an innovative proposed district heating systems. These are the best solutions that can be practically implemented by today. Among these cases, the proposed system so-called nonuniform temperature district heating system can effectively outperform the other solutions in terms of an overall energy-economy point of view. In addition, the project assesses the compatibility of the twin pipes, being used in the currently in-operation district heating systems, with the proposed district heating scheme thermo-hydraulically.