Heat Rejection Subsystem Research Articles

РАЗРАБОТКА КОНЦЕПЦИИ ДВУХФАЗНОЙ СИСТЕМЫ ТЕПЛООТВОДА СПУТНИКА

For spacecraft (SC) with power unit capacity more than 4 ... 6 kW promising construction of thermal control system (TCS) based on two-phase mechanically pumped loops (2PMPL). The development of 2PMPL has been carried out quite intensively since the early '80s. However, so far there are no examples of practical implementation of such high-power systems. One of the main reasons mentioned is the novelty of the system, and insufficient study of its operation in space conditions, which adds risks. The most important component of such systems is a heat rejection subsystem (HRS), whose task is to reject heat from the coolant and radiate it into space. In its turn, HRS is also a system, the design of which requires using a system approach, considering various aspects of its operation. HRS includes a heat-hydraulic network and a radiation heat exchanger (RHE). The key elements of the HRS are condensers (CC), quite new devices for space technology. This paper presents an algorithm for the design and optimization of the heat rejection subsystem (HRS) of a satellite two-phase thermal control system. The methodology of engineering synthesis of complex technical systems and informal procedures for multi-criteria optimization of elements and subsystems at various stages of HRS design is repeatedly used. t is shown that optimization should be carried out both at the level of elements and subsystems, and at the level of the whole thermal control system. As a result of the study, the HRS design is proposed, which uses condensers in the form of smooth steel tubes of constant cross-section and their series-parallel connection scheme in the hydraulic network. Main advantages of the design: traditional for single-phase loops elements are used; operation of elements and subsystems in zero gravity conditions is predictable and allows complete testing on the ground without mandatory flight experiment; the system is operable at high saturation pressures (temperatures) (on ammonia - up to 85℃).

Economic Evaluation of Solar Cooling Schemes

This paper provides an economic evaluation and comparison of ejector, absorption and vapor compression systems driven either partly or fully by solar energy. Life cycle costing has been used to assess the relative economic ranks of eight solar cooling schemes. It has been shown that the capital cost of solar collectors is the dominant capital cost item in the total inventory of solar cooling plant, which has a strong influence on the system life cycle costs. Lower collector costs are therefore critical in establishing economically viable solar cooling systems. Primary energy analysis has been carried out and the running costs of chillers were determined for the maximum range of thermal and electric solar fractions and a number of annual equivalent full load hours of operation. The results indicate that two low temperature flat-plate collector assisted single-effect absorption chillers compete favorably with a PV assisted centrifugal mechanical compression chiller across the maximum range of thermal and electrical solar fractions. Low temperature options for solar cooling have been shown to be more economical than their high temperature counterparts. At current collector prices, solar cooling systems are still not cost effective compared with conventional centrifugal cooling systems, however, it is shown that at a collector cost of £57/m2 for thermal energy and £1.8/Wp for electrical energy, single-effect solar absorption and PV-centrifugal compression could become cost effective within an annual EFLH of 5840 hours. As such, the paper presents technical guidance on the procurement and operation of solar cooling plant. The novel energy and cost calculation methodology developed here can be applied globally to a wide range of solar collectors, chillers, heat rejection and ancillary subsystems.

A Power Conversion Concept for the Jupiter Icy Moons Orbiter

The Jupiter Icy Moons Orbiter (JIMO) mission is currently under study by the Office of Space Science under the Project Prometheus Program. JIMO is examining the use of Nuclear Electric Propulsion (NEP) to carry scientific payloads to three Jovian moons. A potential power system concept includes dual 100 kWe Brayton converters, a deployable pumped loop heat rejection subsystem, and a 400 Vac Power Management and Distribution (PMAD) bus. Many trades were performed in aniving at this candidate power system concept. System-level studies examined design and off-design operating modes, determined startup requirements, evaluated subsystem redundancy options, and quantified the mass and radiator area of reactor power systems from 20 to 200 kWe. In the Brayton converter subsystem, studies were performed to investigate converter packaging options, and assess the induced torque effects on spacecraft dynamics due to rotating machinery. In the heat rejection subsystem, design trades were conducted on heat transport approaches, material and fluid options, and deployed radiator geometries. In the PMAD subsystem, the overall electrical architecture was defined and trade studies examined distribution approaches, voltage levels, and cabling options.

Superconducting magnetic energy storage for BPA transmission line stabilization

The Bonneville Power Administration (BPA) operates the electrical transmission system that joins the Pacific Northwest with southern California. A 30 MJ (8.4 kWh) Superconducting Magnetic Energy Storage (SMES) unit with a 10 MW converter is being installed at the Tacoma Substation to provide system damping for low frequency oscillations of 0.35 Hz. The integrated system status is described and reviewed. Components included in the system are the superconducting coil, seismically mounted in an epoxy fiberglass nonconducting dewar; a helium refrigerator; a heat rejection subsystem; a high pressure gas recovery subsystem; a liquid nitrogen trailer; the converter with power transformers and switchgear; and a computer system for remote microwave link operation of the SMES unit.

An analysis and design of implantable blood heat exchangers for artificial hearts

The use of radioisotopic fueled power conversion systems in long lived artificial hearts are currently being studied by a number of AEC and NHLI contracts. All of these systems require a heat rejection subsystem to remove waste heat. A parametric analysis of an implantable blood heat exchanger was carried out to determine the problem areas and to arrive at a blood heat exchanger design. Biological and physiological design constraints were first established. The parametric analyses showed that the thoracic and abdominal aortic regions are needed for the transfer of relatively large amounts of heat (up to 50 W). Blood heat exchanger designs are presented for the rejection of 25 and 50 W of waste heat.