ZAP Lab

Recently, the application of CubeSat spans from atmospheric probe, to relay communication，to end up the deep space exploration. Accordingly, the requirement of propulsion system in CubeSat moves from simple attitude control, Hoffmann transfer, and deep space navigation. The required thrust is decreasing, but required specific impulse is increasing in order to meet the propulsion requirement.  However, pulsed plasma thruster (PPT) and vacuum cathode arc thruster (VCA) are the promising candidates for the electric propulsion of CubeSat. The discharge process and plasma formation of PPT and VCA are strongly related to discharge chamber configuration, ignition fashion, and propellant sort.

Integrating the past experience on engaging researches related to plasma-stabilized flame and electrical propulsion, and technical supports as well as equipment from Aerospace Science and Technology Research Center (NCKU), Plasma and Space Science Center (NCKU) and Institute of Space Systems (University of Stuttgart, Germany) can accelerate the accomplishment of the electric propulsion prototype system. Eventually, it is expected to integrate our proposed micro plasma thruster in second IRS-CubeSat, and launch into low earth orbit. In addition, this project is initiated to bridge the bilateral collaboration between two universities on the electric propulsion topic. 

RF Ion Thruster https://youtu.be/-VS_X8AhOPw / https://youtu.be/jUkbT5sFeOA

 Vacuum Cathode Arc Thruster https://youtu.be/WXyReJJjLOU

Pulsed Plasma Thruster https://youtu.be/xqkpiVDA5HI

Dr. Li proposed and designed various small-scale reactors for burning gaseous and liquid fuels, and assembled with thermophotovotalic cells to further generate electricity output.  Implanting a porous cap in a small-scale combustor can function as liquid fuel injector, and double as flame stabilizer. A reverse tube was used to redirect flus gas for heating up the combustion chamber. It resulted in the discovery of highly luminous and uniform emitting chamber which is suable for being an emitter in the micro-TPV power system. Many outstanding outcomes have published in renowned international journals. Accordingly, Dr. Li was invited to be the co-author in chapter 8 of monograph titled as “Microscale Combustion and Power Generation”. Besides, Dr. Li also used a quartz tube coating metal-oxide layer and played as an emitter to replace silicon carbide. The advantage of metal-oxide-coating quartz tube has characteristics of easy-to-manufacturing and relatively high heat transfer compared to conventional SiC tube. Furthermore, Dr. Li added Iron carbonyl in liquid heptane in order to enhance flame emission and light intensity in visible wavelengths. This approach can compensate the low quantum efficiency of emitter in the visible wavelength section. A small-scale platinum tube with a novel mechanism is also implemented to the small-scale TPV power system. The following flow chart is shown the important findings and outcomes on the development of a small-scale TPV power system.

Regarding the development of mesoscale to microscale combustors, our research team has proposed the use of segmented catalysts combined with cavity structures in microchannels. We investigated the effects of various operating conditions such as tube diameter, wall material, and flow rate. The catalytic walls influence gas-phase combustion in two primary ways: on one hand, they consume fuel and inhibit gas-phase combustion, while on the other hand, the high temperatures and free radicals generated by wall reactions facilitate gas-phase combustion within the microchannels.

The combination of segmented catalyst arrangement and cavity effects in microchannels presents significant advantages for methane combustion, including reduced residence time required for a complete reaction. These findings have been published in the Chemical Engineering Journal. Additionally, the segmented catalyst combined with cavity effects also shows substantial benefits for H₂/CO, CH₄/CO, and H₂/CH₄ blended fuels. The related research results have been published in Combustion and Flame and the Proceedings of the Combustion Institute.

For liquid fuel combustion in small-scale burners, our research team has proposed a porous-core liquid film fuel burner. We conducted numerical analyses on porous injectors with different porosities and materials and investigated the mechanisms of flame stabilization in liquid combustion. The relevant papers have been published in the Proceedings of the Combustion Institute and Combustion Science and Technology.

High-energy metal fuels are considered a clean and recyclable energy carrier, acting as a forward-looking reactive material suitable for the future low-carbon economy. These high energy density metal materials hold development potential to replace fossil fuels currently used in the energy sector, addressing the imminent issues of global warming and energy crisis. Additionally, high-energy metal fuels are widely used in space propulsion systems.

The primary aim of this research is to analyze and investigate the combustion behavior of pure iron particles and mixed particles (iron-aluminum and iron-coal) in a methane-air premixed flame. The mixed particles were prepared under a 1:1 weight ratio condition. Thermogravimetric analysis of iron and iron-coal showed similar oxidation processes at relatively low temperature ranges. However, the iron-aluminum mixture exhibited a multi-stage oxidation process.

In the study, micron-sized solid fuels were selected and transported to a stoichiometric methane-air premixed flame under low solid fuel feed rates. The experimental results showed that increasing the solid fuel feed rate altered the premixed flame front. A series of relevant experiments were conducted to explore the interdependence between solid fuels and the methane-air premixed flame, as well as changes in some fundamental combustion phenomena, such as combustion speed, flame temperature, gas emissions, and metal oxide products.

The most significant contribution of this paper is the observation of particle micro-explosion phenomena in the iron-coal mixture combustion in the methane-air premixed flame. It is hypothesized that gases such as carbon monoxide, oxygen, and nitrogen form micro bubbles in the iron particle layer, and during the nucleation and coalescence process, carbon monoxide reacts with oxygen to form iron carbonyl. Since iron carbonyl is a flammable gas, the presence of combustible carbon monoxide and iron carbonyl in the nucleated micro bubbles induces micro-explosion phenomena. The results of this study were published in Combustion and Flame (vol. 228, pp. 364-374, 2021).

Zero-carbon emission technology: Iron/air combustion https://youtu.be/q8xSQA5PF84

Regarding the development of biomass technology, Dr. Li emphasized the development of bio-fuel application. In his opinion, the technology of bio-fuel production is sophisticated and almost commercialized. The biomass feedstock provision and bio-fuel application are two main challenges on the development of biomass energy technology. Dr. Li selected castor, miscanthus as well as rice straw as biomass feedstock based on its abundant resource in Taiwan. He performed a conventional pyrolysis to produce bio-fuels, such as bio-gas, bio-liquid and bio-char. Therefore, Dr. Li utilized bio-gas for self-retrofitted catalyst-combustion gas turbine and generated 1KW electricity output; bio-liquid-fuel for vehicle demonstration and chemical refinery, and bio-char for bio-fertilizer and co-firing with coal in industrial furnaces. The following flow chart is demonstrated the utilization and development of various bio-fuels.