Development of a small power generation system with a miniature-scale swirl burner, controlled heat transfer, and thermoelectric generators

Abstract

Recent advances in small power-consuming electric devices have increased the demand for appropriate, compact, rapidly rechargeable, lightweight, and long-lived power sources with higher energy densities. Hydrocarbon fuels are capable of providing high specific energy density, so combustion-based power generators have received increasing attention as an interesting alternative to batteries. In this study, a small power generation system using a miniature-scale swirl burner, two thermoelectric generators (TEGs), a heat medium, and two water blocks as heat sink has been developed. Various swirl strengths ranging from 0 to 1 are studied to find the optimum swirl number (vane angle) for the blow-out limit. The swirl number related to the greatest stable region is found 0.5 which is associated with the 30 ° vane angle for the 3D printed axial swirlers. Because normal-butane is easily liquified and stored, and is in the gas phase at room temperature and atmospheric pressure, it is chosen as the fuel. This paper examines the effect of three thermal input powers of 194 , 291 , and 388 W along with various airflow rates on the performance of the power generation system at the 30 ° vane angle swirler. The results show that about 3 min is needed for our system to reach a steady power output. Moreover, it is observed that the maximum output power is found at the load resistance of R load = 3 Ω for studied operating conditions. Besides, it is shown that by considering the airflow rate fixed, the power output of the system increases with an increase in the fuel flow rate (thermal input power). Furthermore, a maximum power output of 17.2 W is obtained for the fuel flow rate and an airflow rate of 0.200 slpm ( ≈ 388 W ) and 2.7 slpm , respectively, which corresponds to a conversion efficiency of about 4.5 % at R = 3 Ω load resistance.

Properties of turbulent non-premixed methane/air flames in a miniature-scale swirl burner under different coaxial airflow swirl numbers

“…Moreover, the swirl-induced recirculation zone may function as a heat source, causing heated products to interact with fresh reactants upstream [17]. Because of high energy density of hydrocarbon fuels, combustion-based micro-power devices are a more attractive option for portable power generation than rechargeable batteries [18][19][20][21][22]. In these systems, swirling flows are one method for flame stabilization [23][24][25][26][27][28][29][30].…”

Effects of coaxial airflow swirl number on combustion and flame characteristics of methane/air and n-butane/air flames in a miniature-scale swirl burner

“…This results from accurate micro-manufacturing technologies and high energy density of hydrocarbon fuels. These systems can be divided into two groups: (1) direct energy conversion modules such as micro gas turbines and rotary engines and (2) indirect energy conversion ones such as thermoelectric and thermophotovoltaic generators [2][3][4][5]. The energy density of typical hydrocarbon fuels is as much as 50 to 100 times more than rechargeable batteries, so combustion-based micropower generators even with low chemical-to-electrical conversion efficiency are an attractive solution for portable power generation [6][7][8][9].…”

Comparative Study on Combustion and Flame Characteristics of Laminar Methane/Air and N-Butane/Air Flames in a Micro-Slot Burner

“…Typical hydrocarbon fuels have an energy density around 100 times that of the most modern batteries. Despite the heat losses associated with harvesting energy from fuel combustion, a microscale combustion system has been deemed a potential alternative to batteries [1][2][3][4][5]. Understanding the mechanics of laminar micro-fames is critical for developing such combustion devices because multiple micro-fames may be utilized concurrently to improve a heat source's overall heating efectiveness [6].…”