Solar energy harvesting on-board small satellites

Small satellites are receiving increased recognition in the space domain due to their reduced associated launch costs and shorter lead time when compared to larger satellites. However, this advantage is often at the expense of mission capabilities, such as available electrical power and propulsion. A possible solution is to shift from the conventional solar photovoltaic and battery configuration to a micro-Organic Rankine Cycle (ORC) and thermal energy storage system that uses the waste energy from a solar thermal propulsion system. However, limited literature is available on micro-ORC systems, which are capable of producing a few hundred Watts of electrical power. This paper describes the proposed system layout and model of the integrated micro-ORC system, for various working fluids such as Toluene, Hexamethyldisiloxane (MM), and Octamethylcyclotetrasiloxane (D4). Toluene has been identified as a promising working fluid candidate resulting in a power generation system volume fraction of 18% for a 215 kg Low Earth Orbit satellite. The micro-ORC system is capable of producing 200 W of electrical power. The design provides high specific energies of at least 500 Wh/kg but, has a low shared specific power of 10 W/kg. A preliminary design of the micro-turbine provides a conservative total-to-static efficiency of 57%.</p

Draft Seagrass Bibliography Data Base

The following report describes in detail the elements of a literature search performed for the Southwest Florida Water Management District (SWFWMD), Department of Surface Water Improvement and Management (SWIM). The work was performed in accordance with the agreement between the District and Mote Marine Laboratory (MML), and comprises Task 3.0 (Literature Search) of the project entitled, Tampa Bay Water Quality Assessment- Determination of Environmental Requirements of Selected Populations

Draft Seagrass Bibliography Data Base

The following report describes in detail the elements of a literature search performed for the Southwest Florida Water Management District (SWFWMD), Department of Surface Water Improvement and Management (SWIM). The work was performed in accordance with the agreement between the District and Mote Marine Laboratory (MML), and comprises Task 3.0 (Literature Search) of the project entitled, Tampa Bay Water Quality Assessment- Determination of Environmental Requirements of Selected Populations

Design of a Solar Thermal Propulsion and Power System for Mini-satellite Lunar Orbit Insertion

Small satellites with increased capabilities in terms of power and propulsion are being demanded for future missions. This paper proposes a possible solution which is the design of a novel integrated solar thermal system that co-generates propulsion and power on-board mini satellites. The system consists of a solar thermal propulsion system (STP) coupled with a micro-Organic Rankine Cycle (ORC) system to harness the waste heat from the STP receiver to provide electrical power and mitigate the need for solar panels. STP provides an alternative to conventional propulsion systems for missions requiring velocity changes of between 800 m/s and 2500 m/s. Additional advantages include higher specific impulses than chemical propulsion systems, throttability, re-start capabilities, and faster transfer times than electrical propulsion systems. The faster transfer times are especially useful for missions that travel across high radiation regions such as the Van Allen Belt. This unique configuration shares resources such as the concentrator and receiver to potentially extend the power and propulsion capabilities while adhering to the strict mass and volume constraints of small satellites. However, there is currently no literature available on the design process of the proposed bi-modal system. This paper therefore presents an integrated solar thermal design strategy for a Geostationary Transfer Orbit to Lunar orbit insertion mission. The design methodology is described in detail to assist with future evaluations of integrated solar thermal systems for other applications and missions. The system is designed to provide a velocity increment of 1.6 km/s. Five mini-satellite sizes were investigated with a gross wet mass of 100 kg, 200 kg, 300 kg, 400 kg, and 500 kg respectively. Each satellite requires to produce an electrical power of 1 W/kg. The STP system uses water as the propellant due to its safety and performance attributes. Toluene has been selected as the working fluid for the ORC due to its high thermal efficiency. By incorporating the use of a high-temperature receiver, propellant temperatures around 2500 K can be achieved that can produce high specific impulse values of more than 300 s. The design has been optimized for various design parameters, such as propellant temperature, nozzle area ratio, burn time, concentrator design, and ORC cycle pressures. The optimization provides an initial framework in the selection of an optimal integrated solar thermal design for the proposed Lunar mission. An analysis of variance has also been conducted to identify which system parameters, such as optical efficiency and turbine efficiency, have the most influential effect on the system. The heaviest components of the system are the propellant (40 to 50%), concentrator (8%), and insulation (8%) with respect to the gross mass of the satellite.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Space Systems EgineeringFlight Performance and PropulsionSpace Engineerin

Design and characterisation of a bi-modal solar thermal propulsion and power system for small satellites

Small satellites with increased capabilities in terms of power and propulsion are being demanded for future missions. This paper addresses an alternative bi-modal solution which consists of a solar thermal propulsion system coupled with a micro-Organic Rankine Cycle system, to co-generate thrust and electrical power. Current literature on bi-modal systems is limited to static power conversion systems such as thermionic conversion processes. Therefore, this paper expands the research of bi-modal systems to dynamic power conversion systems and latent heat storage systems. The paper documents the design process, key design parameters, and feasibility of this system for a Geostationary Transfer Orbit to Lunar Orbit insertion mission. The results of a single-objective optimisation show the system is most suitable on-board small satellites with a gross mass above 300 kg. The propellant accounts for 50% of the total system mass. The final design uses Silicon as the latent heat energy storage system due to its high specific energy of more than 250 Wh/kg. Additionally, the enthalpy method is used to describe the dynamic behaviour of the phase change material and results show the insulation thermal conductivity has the largest effect, up to 17%, on the receiver's maximum achievable steady-state temperature.Space Systems EgineeringFlight Performance and PropulsionSpace Engineerin

Feasibility of an On-Board Micro-ORC System for Small Satellites

Small satellites are receiving increased recognition in the space domain due to their reduced associated launch costs and their shorter lead time when compared to larger satellites. However, this advantage is often at the expense of mission capabilities, such as available electrical power and propulsion. A possible solution is to change from the conventional solar photovoltaic and battery configuration to a microOrganic Rankine Cycle (ORC) and thermal energy storage system that uses the waste energy from a solar thermal propulsion system. This unique approach has the potential to offer higher system efficiency and power density. However, limited literature is available on microORC systems, which are capable of producing a few hundred Watts of electrical power, especially for small satellites. A feasibility study of these systems and a fluid selection study were conducted. This was done by using a multiobjective genetic algorithm to optimise an onboard microORC system for various working fluids such as Toluene (C7H8), Hexamethyldisiloxane (MM), and Octamethylcyclotetrasiloxane (D4). The two objective functions were to minimise the total volume and maximise the thermal energy storage capacity. This paper describes the proposed system layout and model of the integrated microORC system. The specific objectives of this study are: i) the working fluid selection, and ii) the optimisation of the proposed system incorporating the design of the thermodynamic cycle and the sizing of the turbine and heat exchangers. Results show that the design of the microORC system is dependent on the mission designer requirements, and various design configurations are provided from the Pareto frontier. It was also found that when the surface wall temperature of the evaporator is near the thermal stability limit of the working fluid, the evaporator operates in the dispersed film boiling regime which reduces the heat transfer coefficient. Additional challenges include high microturbine rotational speeds, large thermal cycling, small blade heights, and large condensers. Finally, the storage configuration of the concentrator was identified as crucial for the feasibility of the system onboard small satellites.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Space Systems EgineeringFlight Performance and PropulsionSpace Engineerin