Active heat exchange system development for latent heat thermal energy storage

Various active heat exchange concepts were identified from among three generic categories: scrapers, agitators/vibrators and slurries. The more practical ones were given a more detailed technical evaluation and an economic comparison with a passive tube-shell design for a reference application. Two concepts selected for hardware development are a direct contact heat exchanger in which molten salt droplets are injected into a cooler counterflowing stream of liquid metal carrier fluid, and a rotating drum scraper in which molten salt is sprayed onto the circumference of a rotating drum, which contains the fluid heat sink in an internal annulus near the surface. A fixed scraper blade removes the solidified salt from the surface which has been nickel plated to decrease adhesion forces. Suitable phase change material (PCM) storage media with melting points in the temperature range of interest (250 C to 400 C) were investigated. The specific salt recommended for laboratory tests was a chloride eutectic (20.5KCl-24/5 NaCl-55.0MgCl 2% by wt.), with a nominal melting point of 385 C

Heat pipe radiator

A 15,000 watt spacecraft waste heat rejection system utilizing heat pipe radiator panels was investigated. Of the several concepts initially identified, a series system was selected for more in-depth analysis. As a demonstration of system feasibility, a nominal 500 watt radiator panel was designed, built and tested. The panel, which is a module of the 15,000 watt system, consists of a variable conductance heat pipe (VCHP) header, and six isothermalizer heat pipes attached to a radiating fin. The thermal load to the VCHP is supplied by a Freon-21 liquid loop via an integral heat exchanger. Descriptions of the results of the system studies and details of the radiator design are included along with the test results for both the heat pipe components and the assembled radiator panel. These results support the feasibility of using heat pipes in a spacecraft waste heat rejection system

Active heat exchange system development for latent heat thermal energy storage

Various active heat exchange concepts were identified from among three generic categories: scrapers, agitators/vibrators and slurries. The more practical ones were given a more detailed technical evaluation and an economic comparison with a passive tube-shell design for a reference application (300 MW sub t storage for 6 hours). Two concepts were selected for hardware development: (1) a direct contact heat exchanger in which molten salt droplets are injected into a cooler counterflowing stream of liquid metal carrier fluid, and (2) a rotating drum scraper in which molten salt is sprayed onto the circumference of a rotating drum, which contains the fluid salt is sprayed onto the circumference of a rotating drum, which contains the fluid heat sink in an internal annulus near the surface. A fixed scraper blade removes the solidified salt from the surface which was nickel plated to decrease adhesion forces. In addition to improving performance by providing a nearly constant transfer rate during discharge, these active heat exchanger concepts were estimated to cost at least 25% less than the passive tube-shell design

Space shuttle orbiter heat pipe applications. Volume 2: Final report

For abstract, see

Monogroove heat pipe design: Insulated liquid channel with bridging wick

A screen mesh artery supported concentrically within the evaporator section of a heat pipe liquid channel retains liquid in the channel. Continued and uniform liquid feed to the heat pipe evaporation section (20) during periods of excessive heat transfer is assured. The overall design provides high evaporation and condensation film coefficients for the working fluid by means of the circumferential grooves in the walls of the vapor channel, while not interfering with the overall heat transport capability of the axial groove. The design has particular utility in zero-g environments

Space shuttle heat pipe thermal control systems

Heat pipe (HP) thermal control systems designed for possible space shuttle applications were built and tested under this program. They are: (1) a HP augmented cold rail, (2) a HP/phase change material (PCM) modular heat sink and (3) a HP radiating panel for compartment temperature control. The HP augmented cold rail is similar to a standard two-passage fluid cold rail except that it contains an integral, centrally located HP throughout its length. The central HP core helps to increase the local power density capability by spreading concentrated heat inputs over the entire rail. The HP/PCM modular heat sink system consists of a diode HP connected in series to a standard HP that has a PCM canister attached to its mid-section. It is designed to connect a heat source to a structural heat sink during normal operation, and to automatically decouple from it and sink to the PCM whenever structural temperatures are too high. The HP radiating panel is designed to conductively couple the panel feeder HPs directly to a fluid line that serves as a source of waste heat. It is a simple strap-on type of system that requires no internal or external line modifications to distribute the heat to a large radiating area

Cryogenic thermal diode heat pipes

The development of spiral artery cryogenic thermal diode heat pipes was continued. Ethane was the working fluid and stainless steel the heat pipe material in all cases. The major tasks included: (1) building a liquid blockage (blocking orifice) thermal diode suitable for the HEPP space flight experiment; (2) building a liquid trap thermal diode engineering model; (3) retesting the original liquid blockage engineering model, and (4) investigating the startup dynamics of artery cryogenic thermal diodes. An experimental investigation was also conducted into the wetting characteristics of ethane/stainless steel systems using a specially constructed chamber that permitted in situ observations

Development of alginate beads for probiotic encapsulation: influence of different parameters in the beads size

In the present study different parameters were evaluated in the formation of alginate beads by ionotropic gelation (external extrusion). The size of alginate beads was determined and results showed that needle-CaCl2 solution distance, flow rate, sodium alginate concentration, needle diameter and molecular weight of sodium alginate influenced alginate beads formation. Moreover, was concluded that needle diameter was the parameter that most influenced the beads mean size

High-pressure synthesis, structural and complex magnetic properties of the ordered double perovskite Pb2NiReO6

The ordered double perovskite Pb2NiReO6 has been prepared at 6 GPa and temperatures ranging from 1273 to 1373 K. Its crystal structure determined by X-ray powder diffraction and selected area electron diffraction shows monoclinic symmetry with centrosymmetric space group I2/m (a = 5.6021(1) Å, b = 5.6235(1) Å, c = 7.9286(1) Å and β = 90.284°(1)). High angle annular dark field microscopy studies reveal the existence of compositional microdomains. The compound displays a re-entrant spin-glass transition from a ferrimagnetic ordering below TN 37 K between the Re+5 and Ni+3 (high spin configuration) magnetic sublattices to a spin-glass configuration. Magnetic field dependent magnetization measurements revealed wasp-waisted hysteresis loops at 5 K. These shaped features originate from the antiferromagnetic/ferromagnetic (AFM/FM) competing interactions

El acondicionamiento acústico en el proyecto de un espacio deportivo cubierto

A menudo las instalaciones deportivas se utilizan para actividades culturales o sociales que requieren exigencias acústicas más determinadas. Además el confort acústico durante las competiciones deportivas, tanto para los deportistas como para los espectadores, muchas veces es obviado en el proceso de diseño y acondicionamiento de este tipo de espacios. El objetivo de este trabajo es presentar las condiciones acústicas obtenidas en un pabellón polideportivo recientemente inaugurado, el de Puente Genil (Córdoba), fruto de la colaboración con el arquitecto autor del proyecto y dirección de las obras R. Alario. Estos resultados se han evaluado mediante una medida realiza in situ una vez ejecutada la obra. Ponencia presentada en el Encuentro Ibérico de Acústica. EAA Symposium. Tarrasa, 2005.Frequently the sport installations are used for other cultural or social activities that demand special acoustics requirements. In the other hand, the acoustic comfort for both, sportsmen and spectators, require taken into account the acoustics behavior of these spaces. The objective of this work is to present the process of design of a sport pavilion and the results attained. These results are valuated by means of “in situ” measurement before the pavilion is achieved