An experimental study of the drag reducing surfactant for district heating and cooling

Drag reducing surfactants can be applied to decrease pressure losses in closed circulation pipelines systems like district heating and cooling. This article represents empirical lab scale study of the two drag reducing products developed by AkzoNobel (Sweden) specifically for aqueous solutions for different temperature ranges. Two main issues stopped previous researches of drag reducing agents: heat transfer reduction in shell and tube heat exchanger and environmental concerns. Current shift to heat supply based on renewable energy sources and small-scale biogas CHP plants will no longer require such kind of heat exchangers. It opens opportunities for new surfactants and its application in district heating. This research outlines environmental properties of the two surfactants including its biodegradability rates

Optimization of a Hybrid Energy System with District Heating and Cooling Considering Off-Design Characteristics of Components, an Effort on Optimal Compressed Air Energy Storage Integration

In this work, the optimal design of a hybrid energy complex, including wind turbines, an internal combustion engine, and an adiabatic compressed air energy storage system is investigated. A novel bi-level optimization strategy is proposed for optimizing the capacity and operational power of each component of the system based on techno-economic considerations. The article presents information and discussions about the impacts of the partial-load operation of the energy storage system components on the optimal rated power and working strategies. The off-design characteristics are proven to have a huge negative impact on the efficiency and economy of the hybrid system. The efficiency reduction of the compressed air energy storage system is about 21% in summer and 8.9% in winter, when the system is operating in partial-load conditions. The operation cost of the system is reduced significantly when carrying out the proposed bi-level optimization strategy