Efficiency enhancement in existing biomass organic Rankine cycle plants by means of thermoelectric systems integration

Abstract

This work investigates, from a thermodynamic point of view, the possibility of integrating thermoelectric systems (TES) in existing solid biomass-fuelled ORC CHP plants in a cost-effective way. Thus, a simple plant layout was proposed. The benefits achieved in the overall plant performance, constrained by several technical parameters of the subsystems involved, are assessed in terms of the Second Law efficiency and other characteristic parameters such as the First Law efficiency and the Primary Energy Savings Ratio. The main conclusion obtained is anticipating the fact that exists a certain optimal TES driving temperature value leading to the maximisation of the plant's performance. According to the specific results extracted from the examples evaluated (TES integrated in Toluene and MDM ORC CHP plants), this temperature is about 245 • C and 210 • C, respectively, which leads to an increase in the overall Second Law efficiency of the plant up to 7-8%. Hence, it is clear that thermoelectric systems can contribute to the enhancement of the performance and to do so, there are guidelines to be considered prior to the detailed design of such systems to be integrated in existing ORC CHP plants.

Design of Radial-Inflow Turbines for Low-Temperature Organic Rankine Cycle

“…They designed and tested several small solar ORC systems with monochlorobenzene as the working fluid, and the system power outputs were 2 kW and 10 kW. Since then, ORC has been widely used for heat recovery from low-temperature sources, including biomass combustion [2][3][4], geothermal heat [5,6], industrial waste heat [7,8], and solar thermal heat [9][10][11][12]. The working fluid used in the ORC system plays a very important role in the overall cycle efficiency.…”

Performance comparison of thermal power generation‐organic Rankine cycle combined cycle system for ships waste heat utilization under different bottom cycle ratios

“…Although the TEG had advantages such as a straightforward design, no moving parts, a long lifespan, and low maintenance costs, it also had the lowest efficiency (4%). 12 The ORC technology also has significant advantages when it comes to recycling waste heat. Yang et al 13 utilized six working fluids to recycle waste heat from the cylinder jacket water, and the R600a showed the most satisfying results.…”

“…To increase the system's output power, Marvo et al, 9 Shu et al, 10 and Borcuch et al 11 improved the internal fin structure of the TEG. Although the TEG had advantages such as a straightforward design, no moving parts, a long lifespan, and low maintenance costs, it also had the lowest efficiency (4%) 12 …”