40 K Neon liquid energy storage unit

Cryocoolers have been progressively replacing the use of the stored cryogens in cryogenic chains used for detector cooling, thanks to their higher and higher reliability. However, the mechanical vibrations, the electromagnetic interferences and the temperature fluctuations inherent to their functioning could reduce the sensor’s sensitivity. In order to minimize this problem, compact thermal energy storage units (ESU) are studied, devices able to store thermal energy without significant temperature increase. These devices can be used as a temporary cold source making it possible to turn the cryocooler OFF providing a proper environment for the sensor. A heat switch is responsible for the thermal decoupling of the ESU from the cryocooler’s temperature that increases when turned OFF. In this work, several prototypes working around 40 K were designed, built and characterized. They consist in a low temperature cell that contains the liquid neon connected to an expansion volume at room temperature for gas storage during the liquid evaporation phase. To turn this system insensitive to the gravity direction, the liquid is retained in the low temperature cell by capillary effect in a porous material. Thanks to pressure regulation of the liquid neon bath, 900 J were stored at 40K. The higher latent heat of the liquid and the inexistence of triple point transitions at 40 K turn the pressure control during the evaporation a versatile and compact alternative to an ESU working at the triple point transitions. A quite compact second prototype ESU directly connected to the cryocooler cold finger was tested as a temperature stabilizer. This device was able to stabilize the cryocooler temperature ((≈ 40K ±1 K) despite sudden heat bursts corresponding to twice the cooling power of the cryocooler. This thesis describes the construction of these devices as well as the tests performed. It is also shown that the thermal model developed to predict the thermal behaviour of these devices, implemented as a software,describes quite well the experimental results. Solutions to improve these devices are also proposed.

40 K neon liquid energy storage unit

Cryocoolers have been progressively replacing the use of the stored cryogens in cryogenic chains used for detector cooling, thanks to their higher and higher reliability. However, the mechanical vibrations, the electromagnetic interferences and the temperature fluctuations inherent to their functioning could reduce the sensor’s sensitivity. In order to minimize this problem, compact thermal energy storage units (ESU) are studied, devices able to store thermal energy without significant temperature increase. These devices can be used as a temporary cold source making it possible to turn the cryocooler OFF providing a proper environment for the sensor. A heat switch is responsible for the thermal decoupling of the ESU from the cryocooler’s temperature that increases when turned OFF. In this work, several prototypes working around 40 K were designed, built and characterized. They consist in a low temperature cell that contains the liquid neon connected to an expansion volume at room temperature for gas storage during the liquid evaporation phase. To turn this system insensitive to the gravity direction, the liquid is retained in the low temperature cell by capillary effect in a porous material. Thanks to pressure regulation of the liquid neon bath, 900 J were stored at 40K. The higher latent heat of the liquid and the inexistence of triple point transitions at 40 K turn the pressure control during the evaporation a versatile and compact alternative to an ESU working at the triple point transitions. A quite compact second prototype ESU directly connected to the cryocooler cold finger was tested as a temperature stabilizer. This device was able to stabilize the cryocooler temperature ((≈ 40K ±1 K) despite sudden heat bursts corresponding to twice the cooling power of the cryocooler. This thesis describes the construction of these devices as well as the tests performed. It is also shown that the thermal model developed to predict the thermal behaviour of these devices,implemented as a software, describes quite well the experimental results. Solutions to improve these devices are also proposed.

Análise energética do milho em sistema de plantio direto, em assentamento rural, Itaberá/SP

Pós-graduação em Agronomia (Energia na Agricultura) - FCA

Análise energética do milho em sistema de plantio direto, no assenta-mento rural da fazenda pirituba, Itaberá/SP

The aim of this work was to proceed, from the energetic point of view, an analysis of a corn agroecosystem, on the direct planting, located at Pirituba II rural workers placement project, Área III, city of Itaberá/SP. The energetic analysis mesured all operations, together with its fisical demands, the inputs and produced grains, classifying them within their respective flux, based on the definition of energy inputs and outputs, converting them into energetic equivalents and, so, determining the energetic matrix of de agroecosystem. The caloric index used were cultural efficiency and cultural liquid energy. The results showed the dependence of the studied systems on the chemical energy sources, from fertilizers (39,49%), agrotoxics (27,74%), and fossile energy of diesel (24,94%). The energetic values of the direct and indirect energy showed a very big difference between them, what means that the energy sources used in the system are not balanced. The cultural efficiency found was 12,86 and cultural liquid energy got to 115.025,92 MJ x ha-1. Later on, obtained data was compared to already existing data in Bueno (2002), who researched conventional planting system. The cultural inputs of both systems were energeticaly different: 9.696,97 MJ x ha-1 (direct planting), e 8.783,78 MJ x ha-1 (convencional planting). The outputs had very different results: 124.722,89 e 79.118,38 MJ x ha-1, respectively. So, we had much more cultural liquid energy on the studied system: 115.025,92 MJ x ha-1, compared to convencional system: 70.334,60 MJ x ha-1. The energectic loss of nitrogened fertilizers contributed for the high energetic loss of both energetic studied matrices. There are few contribution from biological energy source in both systems.

Energetic analysis of landrace varieties and hybrids of corn produced in different technological levels of management

The aim of this study was to analyze, under the energetic point of view, the cultivation of corn in three management systems (low, medium and high-tech), using two landrace varieties ('Argentino' and 'BR da Várzea'), a double hybrid cultivar (SHS 4080) and a simple hybrid (IAC 8333). Five performance indicators were used: energy efficiency, liquid cultural energy, cultural efficiency, energy balance and productive energy efficiency. From the perspective of family farming, it was verified the largest social importance of the systems under low and medium levels of technology, due to the increase employment capacity of rural labor. The liquid cultural energy and energy balance were more favorable for the system under high technological level, unlike cultural efficiency and productive energy efficiency, which were significantly higher for medium and low technological levels. The variety 'Argentino' showed lower productive energy efficiency. The variety 'BR da Várzea', on the other hand, presented the potential to generate energy as much as the hybrids. In general, the biggest sustainability in the corn crop was achieved when the management system under medium and lower levels of technology were used.

Avaliação energética e custo de produção da cana–de açúcar (Saccharum) do preparo de solo ao 5ºcorte

Pós-graduação em Agronomia (Energia na Agricultura) - FCA

Valor nutritivo e alimentício da silagem de grãos úmidos de milho na alimentação de cabra em lactação

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Custos energéticos do agroecossistema pinhão-manso e milho: comparativo entre o sistema de condução sequeiro e o irrigado

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Solid electrolytes for electrochromic devices based on reversible metal electrodeposition

Air conditioning and lighting costs can be reduced substantially by changing the optical properties of "intelligent windows." The electrochromic devices studied to date have used copper as an additive. Copper, used here as an electrochromic material, was dissolved in an aqueous animal protein-derived gel electrolyte. This combination constitutes the electrochromic system for reversible electrodeposition. Cyclic voltammetry, chronoamperometric and chromogenic analyses indicated that were obtained good conditions of transparency (initial transmittance of 70%), optical reversibility, small potential window (2.1 V), variation of transmittance in visible light (63.6%) and near infrared (20%) spectral regions. Permanence in the darkened state was achieved by maintaining a lower pulse potential (-0.16 V) than the deposition potential (-1.0 V). Increasing the number of deposition and dissolution cycles favored the transmittance and photoelectrochemical reversibility of the device. The conductivity of the electrolyte (10(-3) S/cm) at several concentrations of CuCl2 was determined by electrochemical impedance spectroscopy. A thermogravimetric analysis confirmed the good thermal stability of the electrolyte, since the mass loss detected up to 100 degrees C corresponded to water evaporation and decomposition of the gel started only at 200 degrees C. Micrographic and small angle X-ray scattering analyses indicated the formation of a persistent deposit of copper particles on the ITO. (C) 2012 Elsevier B.V. All rights reserved.

Table 2. Performance summary of K-based sorbents capturing CO2

This article reviews the progress made in CO2 capture, storage, and utilization in Chinese Academy of Sciences (CAS). New concepts such as adsorption using dry regenerable solid sorbents as well as functional ionic liquids (ILs) for CO2 capture are thoroughly discussed. Carbon sequestration, such as geological sequestration, mineral carbonation and ocean storage are also covered. The utilization of CO2 as a raw material in the synthesis of chemicals and liquid energy carriers which offers a way to mitigate the increasing CO2 buildup is introduced.

Determination of Cr, Fe, Co, Ni, Cu, Zn, As and Pb in liquid chemical waste by energy dispersive X-ray fluorescence

A method for simultaneous determination of Cr, Fe, Co, Ni, Cu, Zn, As e Pb in liquid chemical waste using Energy Dispersive X-Ray Fluorescence (EDXRF) technique was evaluated. A small sample amount (200 mu L) was dried on a 6.35 mu m thickness Mylar film at 60 degrees C and the analyses were carried out using an EDXRF spectrometer operated with an X-ray Mo tube (Zr filter) at 30 kV/20 mA. The acquisition time was 300 s and the Ga element was utilized as internal standard at 25 mg/L for quantitative analysis. The method trueness was assessed by spiking and the detection limit for those elements ranged from 0.39 to 1.7 mg/L. This method is notable because it assists the choice of the more appropriated waste treatment procedure, in which inter elemental interference is a matter of importance. In addition, this inexpensive method allows a non-destructive determination of the elements from (19)K to (92)U simultaneously.

Scaling of the elastic contribution to the surface free energy of a nematic liquid crystal on a sawtoothed substrate

We characterize the elastic contribution to the surface free energy of a nematic liquid crystal in the presence of a sawtooth substrate. Our findings are based on numerical minimization of the Landau-de Gennes model and analytical calculations on the Frank-Oseen theory. The nucleation of disclination lines (characterized by non-half-integer winding numbers) in the wedges and apexes of the substrate induces a leading order proportional to q ln q to the elastic contribution to the surface free-energy density, with q being the wave number associated with the substrate periodicity.

Towards cryogenic liquid –vapor energy storage units for space applications

Dissertation to obtain the Doctoral degree in Physics Engineering

40 K Liquid Neon Energy Storage Unit

A thermal Energy Storage Unit (ESU) could be used to attenuate inherent temperature fluctuations of a cold finger, either from a cryocooler working or due to sudden income heat bursts. An ESU directly coupled to the cold source acts as a thermal buffer temporarily increasing its cooling capacity and providing a better thermal stability of the cold finger (“Power Booster mode”). The energy storage units presented here use an enthalpy reservoir based on the high latent heat of the liquid-vapour transition of neon in the temperature range 38 - 44 K to store up to 900 J, and that uses a 6 liters expansion volume at RT in order to work as a closed system. Experimental results in the power booster mode will be described: in this case, the liquid neon cell was directly coupled to the cold finger of the working cryocooler, its volume (12 cm3) allowing it to store 450 J at around 40 K. 10 W heat bursts were applied, leading to liquid evaporation, with quite reduced temperature changes. The liquid neon reservoir can also work as a temporary cold source to be used after stopping the cryocooler, allowing for a vibration-free environment. In this case the enthalpy reservoir implemented (24 cm3) was linked to the cryocooler cold finger through a gas gap heat switch for thermal coupling/decoupling of the cold finger. We will show that, by controlling the enthalpy reservoir’s pressure, 900 J can be stored at a constant temperature of 40 K as in a triple-point ESU.

Energy dispersive X-Ray fluorescence : measuring elements in solid and liquid matrices

The subject of this project is about “Energy Dispersive X-Ray Fluorescence ” (EDXRF).This technique can be used for a tremendous variety of elemental analysis applications.It provides one of the simplest, most accurate and most economic analytical methods for thedetermination of the chemical composition of many types of materials.The purposes of this project are:- To give some basic information about Energy Dispersive X-ray Fluorescence.- To perform qualitative and quantitative analysis of different samples (water-dissolutions,powders, oils,..) in order to define the sensitivity and detection limits of the equipment.- To make a comprehensive and easy-to-use manual of the ‘ARL QUANT’X EnergyDispersive X-Ray Fluorescence’ apparatus