A new receiver concept utilizing impinging jet cooling technology has been developed for a small scale solar dish-Brayton system. In a typical impinging receiver design, the jet nozzles are distributed evenly around the cylindrical absorber wall above the solar peak flux region for managing the temperature at an acceptable level. The absorbed solar irradiation is partially lost to the ambient by radiation and natural convection heat transfer, the major part is conducted through the wall and taken away by the impingement jets to drive a gas turbine. Since the thermal power requirement of a 5 kWe Compower® micro gas turbine (MGT) perfectly matches with the power collected by the EuroDish when the design Direct Normal Irradiance (DNI) input is 800 W/m2, the boundary conditions for the impinging receiver design in this work are based on the combination of the Compower®MGT and the EuroDish system. In order to quickly find feasible receiver geometries and impinging jet nozzle arrangements for achieving acceptable temperature level and temperature distributions on the absorber cavity wall, a novel inverse design method (IDM) has been developed based on a combination of a ray-tracing model and a heat transfer analytical model. In this design method, a heat transfer model of the absorber wall is used for analyzing the main heat transfer process between the cavity wall outer surface, the inner surface and the working fluid. A ray-tracing model is utilized for obtaining the solar radiative boundary conditions for the heat transfer model. Furthermore, the minimum stagnation heat transfer coefficient, the jet pitch and the maximum pressure drop governing equations are used for narrowing down the possible nozzle arrangements. Finally, the curves for the required total heat transfer coefficient distribution are obtained and compared with different selected impinging arrangements on the working fluid side, and candidate design configurations are obtained. Furthermore, a numerical conjugate heat transfer model combined with a ray-tracing model was developed validating the inverse design method and for studying the thermal performance of an impinging receiver in detail. With the help of the modified inverse design method and the numerical conjugate heat transfer model, two impinging receivers based on sintered α-SiC (SSiC) and stainless steel 253 MA material have been successfully designed. The detailed analyses show that for the 253 MA impinging receiver, the average air temperature at the outlet and the thermal efficiency can reach 1071.5 K and 82.7% at a DNI level of 800 W/m2 matching the system requirements well. Furthermore, the local temperature differences on the absorber can be reduced to 130 K and 149 K for two different DNI levels, which is a significant reduction and improvement compared with earlier published cavity receiver designs. The inverse design method has also been verified to be an efficient way in reducing the calculation costs during the design procedure. For the validation and demonstration of the receiver designs, a unique experimental facility was designed and constructed. The facility is a novel high flux solar simulator utilizing for the first time Fresnel lenses to concentrate the light of 12 commercial high power Xenon-arc lamps. Finally, a prototype of a 253 MA based impinging was experimentally studied with the help of the 84 kWe Fresnel lens based high flux solar simulator in KTH. / <p>QC 20151123</p> / Optimised Microturbine Solar Power System , OMSOP

No description available.

Thesis (PhD)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The objective of this research was to develop a neutron detection system that incorporates a mass spectrometer to measure high neutron flux in a nuclear reactor environment. This system consists of slow and fast neutron detector elements for measuring fluxes in those energy regions respectively. The detector should further be capable of withstanding the harsh conditions associated with a high temperature reactor. This novel detector which was initially intended for use in the PBMR reactor has possible applications as an in-core neutron and indirect temperature-monitoring device in any of the HTGR. Simulations of a generic HTGR core model were performed in order to obtain the neutron energy spectrum with emphasis on the behavior of three energy regions, slow, intermediate and fast neutrons within the core at different temperatures. The slow neutron flux which has the characteristic of a Maxwell- Boltzmann distribution were found to shift to larger values of neutron flux at higher energies as the fuel temperature increased, while fast neutron flux spectra remained relatively constant. In addition, the results of the fit of the slow neutron flux with a modified Maxwell-Boltzmann equation confirmed that in the presence of the neutron source, leakage and absorption, the effective neutron temperatures is above the medium temperatures. From these results, it was clear that the detection system will need to monitor both slow and fast neutron flux. Placing neutron detectors inside the reactor core, that are sensitive to a particular energy range of slow and fast neutrons, would thus provide information about the change of temperature in the fuel and hence act as an in-core temperature monitor. A detection mechanism was developed that employs the neutron-induced break-up reaction of 6Li and 12C into α-particles. These materials make excellent neutron converters without interference due to γ-rays, as the contributions from 6Li(γ,np)4He and 12C(γ,3α) reactions are negligible. The mass spectrometer measures the 4He partial pressure as a function of time under high vacuum with the help of pressure gradient provided by a high-vacuum turbomolecular pump and a positive-displacement fore-vacuum pump connected in series. A cryogenic trap, which contains a molecular sieve made of pellets 1.6 mm in diameter, was also designed and manufactured to remove impurities which cause a background in the lighter mass region of the spectrum. The development and testing of the high flux neutron detection system were performed at the iThemba Laboratory for Accelerator Based Sciences (LABS), South Africa. These tests were carried out with a high energy proton beam at the D-line neutron facility, and with a fast neutron beam at the neutron radiation therapy facility. To test the principle and capability of the detection system in measuring high fluxes, a high intensity 66 MeV proton beam was used to produce a large yield of α-particles. This was done because the proton inelastic scattering cross-section with 12C nuclei is similar to that of neutrons, with a threshold energy of about 8 MeV for both reactions. Secondly, the secondary fast neutrons produced from the 9Be(p,n)9B reaction were also measured with the fast neutron detector. The response of this detection system during irradiation was found to be relatively fast, with a rise time of a few seconds. This is seen as a sharp increase in the partial pressure of 4He gas as the proton or neutron beam bombards the 12C material. It was found that the production of 4He with the proton beam was directly proportional to the beam intensity. The number of 4He atoms produced per second was deduced from the partial pressure observed during the irradiation period. With a neutron beam of 1010 s−1 irradiating the detector, the deduced number of 4He atoms was 109 s−1. When irradiation stops, the partial pressure drops exponentially. This response is attributed to a small quantity of 4He trapped in the present design. Overall, the measurements of 4He partial pressure produced during the tests with proton and fast neutron beams were successful and demonstrated proof of principle of the new detection technique. It was also found that this system has no upper neutron flux detection limit; it can be even higher than 1014 n·cm−2·s−1. The lifetime of this detection system in nuclear reactor environment is practically unlimited, as determined by the known ability of stainless steel to keeps its integrity under the high radiation levels. Hence, it is concluded that this high flux neutron detection system is excellent for neutron detection in the presence of high γ-radiation level and provides real-time flux measurements. / AFRIKAANSE OPSOMMING: Die doel van hierdie navorsing was om ’n neutrondetektorstelsel te ontwikkel wat hoë neutronvloed binne in ’n kernreaktor kan meet. Die stelsel bevat twee aparte detektorelemente sodat die termiese sowel as snelneutronvloed gemeet kan word. Die detektor moet verder in staat wees om die strawwe toestande, kenmerkend aan ’n hoë temperatuur reaktor, te kan weerstaan. Die innoverende detektorstelsel, oorspronklik geoormerk vir gebruik in die PBMR reaktor, het toepassingsmoontlikhede as in-kern neutron- sowel as indirekte temperatuurmonitor. Simulasies van ’n generiese model van ’n HTGR reaktorkern is uitgevoer ten einde die neutronenergiespektrum in die kern by verskillende temperature te bekom met klem op die gedrag van neutrone in drie energiegroepe: stadig (termies), intermediêr en snel (vinnig). Daar is bevind dat die stadige neutrone, wat ’n Maxwell-Boltzman verdeling toon, in intensiteit toeneem en dat die piek na hoër energie verskuif met toename in temperatuur, terwyl die vinnige neutronspektrum relatief onveranderd bly. ’n Passing van die stadige spektrum op ’n gemodifiseerde Maxwell-Boltzmann verdeling het bevestig dat die effektiewe neutrontemperatuur weens die teenwoordigheid van bronterme, verliese en absorpsie, hoër as die temperatuur van die medium is. Hierdie resultate maak dit duidelik dat die detektorstelsel beide die stadige sowel as die vinnige neutronvloed moet kan waarneem. Deur detektorelemente wat sensitief is vir die onderskeie spekrale gebiede in die reaktorhart te plaas, kan informasie bekom word wat tot in-kern temperatuur herleibaar is sodat die stelsel inderdaad as indirekte temperatuurmonitor kan dien. Die feit dat alfa-deeltjies geproduseer word in neutron-geïnduseerde opbreekreaksies van 6Li en 12C is as die basis van die nuwe opsporingsmeganisme aangewend. Hierdie materiale funksioneer uitstekend as neutron-selektiewe omsetters in die teenwoordigheid van gamma-strale aangesien laasgenoemde se bydraes tot helium produksie via die 6Li(γ,np)4He en 12C(γ,3α) reaksies, weglaatbaar is. Die massaspektrometer meet die tydgedrag van die 4He parsiële druk binne ’n hoogvakuum wat met behulp van ’n seriegeskakelde kombinasie van ’n turbomolekulêre en positiewe-verplasingsvoorpomp verkry word. ’n Koueval met ’n molekulêre sif, bestaande uit 1.6 mm diameter korrels, is ontwerp en vervaardig om onsuiwerhede te verwyder wat andersins as agtergrond by die ligter gedeelte van die massaspektrum sou wys. Die ontwikkeling en toetsing van die hoëvloed detektorstelsel is te iThembaLABS (iThemba Laboratories for Accelerator Based Sciences) gedoen. Dit is uitgevoer deur gebruik te maak van die hoë energie protonbundel van die D-lyn neutronfasiliteit asook van die bundel vinnige neutrone by die neutronterapiefasiliteit. Om die beginsel en vermoë te toets om by ’n hoë neutronvloed te kan meet, is van die intense 66 MeV protonbudel gebruik gemaak om ’n hoë opbrengs alfa-deeltjies te verkry. Dit is gedoen omdat die reaksiedeursnit vir onelastiese verstrooiing van protone vanaf 12C kerne soortgelyk is aan die van neutrone, met ’n drumpelenergie van 8 MeV vir beide reaksies. Tweedens is die sekondêre vinnige neutrone afkomstig van die 9Be(p,n)9B reaksie ook met die neutrondetektor gemeet. Daar is bevind dat die reaksietyd van die deteksiestelsel tydens bestraling relatief vinnig is, soos gekenmerk deur ’n stygtyd van etlike sekondes. Laasgenoemde manifesteer as ’n toename in die parsiële druk van die 4He sodra die proton- of neutronbundel op die 12C teiken inval. Daar is verder bevind dat die 4He produksie direk eweredig aan die bundelintensiteit is. Vir ’n neutronbundel van nagenoeg 1010 s−1, invallend op die neutrondetektor, is vanaf die gemete parsiële druk afgelei dat die produksie van 4He atome sowat 109 s−1 beloop. In die geheel beoordeel, was die meting van die 4He parsiële druk tydens die toetse met vinnige protone en neutrone suksesvol en het dit die nuwe meetbeginsel bevestig. Dit is verder bevind dat die meetstelsel nie ’n beperking op die boonste neutronvloed plaas nie, maar dat dit vloede van selfs hoër as 1014 s−1 kan hanteer. Die leeftyd van die detektorstelsel in die reaktor is prakties onbeperk en onderhewig aan die bevestigde integriteit van vlekvrystaal onder hoë bestraling. Die gevolgtrekking is dus dat die nuwe detektorstelsel uitstekend geskik is vir die in-tyd meting van ’n baie hoë vloed van neutrone ook in die teenwoordigheid van intense gammabestraling.

Segundo o Atlas Brasileiro de Energia Solar, apesar das diferentes características climáticas observadas no Brasil, pode-se constatar que a média anual de irradiação solar global apresenta boa uniformidade e elevados índices por todo o país. Os valores desta grandeza em quase toda a extensão do território brasileiro (4200-6700 Wh/m2/dia) são superiores aos da maioria dos países da União Europeia, como Alemanha (900-1250 Wh/m2/dia), França (900-1650 Wh/m2/dia) e Espanha (1200-1850 Wh/m2/dia), onde projetos para aproveitamento de energia solar, alguns contando com fortes incentivos governamentais, são amplamente disseminados. Grande parte dos avanços científicos obtidos nos estudos sobre aproveitamento da energia solar se deve à utilização de simuladores solares compactos nos experimentos de longa duração. Ao substituir o Sol por fontes artificiais, como lâmpadas capazes de emitir radiação próxima à solar, os simuladores eliminam a dependência de fatores naturais como condições climáticas, horário do dia, intermitência e movimento de direção da radiação solar. O projeto proposto para esta dissertação de Mestrado teve como objetivo o domínio do processo de concepção e fabricação de um simulador solar concentrador formado por lâmpadas e um refletor ótico. Uma vez dominada a técnica, um modelo piloto de simulador solar foi construído e alguns testes executados para avaliar a qualidade do projeto, a resistência dos componentes e o fator de concentração do aparato. / According to the Brazilian Atlas of Solar Energy, despite the different climatic characteristics observed in Brazil, the annual average of global solar irradiation has good uniformity and high levels throughout the country. The values of global solar irradiation in almost the entire length of Brazil (4200-6700 Wh/m2/day) are higher than those observed in most European Union countries, like Germany (900-1250 Wh/m2/day), France (900-1650 Wh/m2/day) and Spain (1200-1850 Wh/m2/day), where projects for solar energy applications, some of them relying on strong government incentives, are widely disseminated. Several scientific and technological advances made in the study of solar energy applications are due to the use of compact solar simulators in long-term experiments. Replacing the Sun by artificial sources, such as arc lamps with radiation emission similar to the Sun spectrum, indoor simulators avoid the dependence on natural conditions such as the weather, the daytime, the sunlight intermittence and the directional change of the solar radiation. The project proposed for this dissertation aimed to master the design and manufacturing processes of a high-flux solar simulator consisting of arc lamps and an optical reflector. Once technique was understood, a solar simulation pilot model was built and some tests were performed to assess the project quality, the resistance of components and the apparatus concentration factor.

L'apparition des détecteurs à comptage de photons X à base de CdTe avec des capacités de discrimination de l'énergie des photons ouvre de nouvelles perspectives pour l'imagerie radiographique. Les applications médicales et en contrôle de bagages X sont caractérisées par un flux de photons X très élevé, et exigent par conséquent une mise en forme très rapide du photo-courant mesuré pour limiter les empilements. Cependant, si cette mise en forme est plus courte que le temps de transit des électrons dans le semi-conducteur, la charge mesurée devient inférieure à la charge déposée : c’est le déficit balistique. Par ailleurs, la variation dans le temps du profil du champ électrique dans le volume du détecteur entraîne une augmentation du temps de transit des électrons. En conséquence, la charge mesurée diminue dans le temps, faussant la mesure de l’énergie des photons X. L’objectif de ce travail est de caractériser cette instabilité et de développer une méthode de correction de son effet sur les spectres en énergie. Nous avons proposé un algorithme de correction basé sur l'utilisation de deux Lignes à Retard (LAR). Une LAR rapide (50ns ?) permet de mesurer les spectres X à très fort flux sans compromis sur le taux de comptage. Une LAR lente (200ns ?) est utilisée pour mesurer intégralement la charge déposée sans déficit balistique. Un facteur de correction est évalué et utilisé pour stabiliser la mesure de l’énergie des X avec la LAR rapide. Une étape importante de cet algorithme consiste à trier les impulsions traitées pour rejeter celles qui peuvent dégrader la mesure de ce facteur de correction, notamment les empilements. La méthode proposée a été implémentée dans un FPGA pour fonctionner en temps réel et a été testée avec un détecteur CdTe de 3mm d'épaisseur avec 4×4 pixels au pas de 800 microns, capable de mesurer des spectres X dans la gamme d'énergie 20-160 keV avec 256 canaux d'énergie. La méthode développée a été initialement testée à faible taux de comptage avec des sources gamma Co-57 et Am-241, puis à fort taux de comptage jusqu'à ~2 Mc/s avec un tube à rayons X. Cet algorithme innovant a montré sa capacité de fournir une réponse stable du détecteur dans le temps sans affecter la résolution d'énergie (7 % à 122 keV) et le temps mort (~70 ns). / The emergence of CdTe Photon Counting Detectors (PCD) with energy discrimination capabilities, opens up new perspectives in X-ray imaging. Medical and security applications are characterized by very high X-ray fluxes and consequently require a very fast shaper in order to limit dead time losses due to pile-up. However, if the shaper is faster than the collection of the charges in the semiconductor, there is a loss of charge called ballistic deficit. Moreover, variations of the electric field profile in the detector over time cause a change in the collection time of the charges. As a result, the conversion gain of the detector will be affected by these variations. The instability of the response is visible over time as a channel shift of the spectra, resulting in a false information of the photon energy. The aim of this work is to characterize this instability in order to understand the mechanisms behind them and to develop a method to correct its effect. We proposed a correction algorithm based on the use of two Single Delay Line (SDL) shaping amplifiers. A fast SDL is used to measure the X-ray spectra at high count rates with limited count rate losses. A slow SDL is used to measure the full collected charge in order estimate a correction factor for the compensation of the ballistic deficit fluctuations of the fast SDL. An important step is to sort the processed pulses in order to reject pile-up and other undesirable effects that may degrade the measurement of the correction factor. The proposed method was implemented in an FPGA in order to correct the ballistic deficit in real-time and to give a stable response of the detector at very high fluxes. The method was tested with a 4x4 pixels detector (CdTe) of 3 mm thickness and 800 micron pitch, which is able to measure transmitted X-ray spectra in the energy range of 20-160 kV on 256 energy bins. The developed method was initially tested at low count rate with a Co-57 and an Am-241 gamma-ray sources, then at high count rates up to ~2 Mc/s with an X-ray source. With the characterization and the validation of this innovative algorithm we prove its ability in providing a stable response of the detector over time without affecting the energy resolution (~7% at 122 keV) and the dead time (~70 ns).

High precision measurements of a weak interaction decay were conducted to search for possible variation of the decay rate parameter caused by an antineutrino flux. The experiment searched for variation of the ⁵⁴Mn electron capture decay rate parameter to a level of precision of 1 part in ∼10⁵ by comparing the difference between the decay rate in the presence of an antineutrino flux ∼3×10¹² cm^-2sec^-1 and no flux measurements. The experiment is located 6.5 meters from the reactor core of the High Flux Isotope Reactor (HFIR) in Oak Ridge National Laboratory. A measurement to this level of precision requires a detailed understanding of both systematic and statistical errors. Otherwise, systematic errors in the measurement may mimic fundamental interactions. <div><br></div><div>The gamma spectrum has been collected from the electron capture decay of ⁵⁴Mn. What differs in this experiment compared to previous experiments are, (1) a strong, uniform, highly controlled, and repeatable source of antineutrino flux, using a reactor, nearly 50 times higher than the solar neutrino flux on the Earth, (2) the variation of the antineutrino flux from HFIR is 600 times higher than the variation in the solar neutrino flux on the Earth, (3) the extensive use of neutron and gamma-ray shielding around the detectors, (4) a controlled environment for the detector including a fixed temperature, a nitrogen atmosphere, and stable power supplies, (5) the use of precision High Purity Germanium (HPGe) detectors and finally, (6) accurate time stamping of all experimental runs. By using accurate detector energy calibrations, electronic dead time corrections, background corrections, and pile-up corrections, the measured variation in the ⁵⁴Mn decay rate parameter is found to be δλ/λ=(0.034±1.38)×10^-5. This measurement in the presence of the HFIR flux is equivalent to a cross-section of σ=(0.097±1.24)×10^-25cm². These results are consistent with no measurable decay rate parameter variation due to an antineutrino flux, yielding a 68% confidence level upper limit sensitivity in δλ/λ <= 1.43×10^-5 or σ<=1.34×10^-25cm² in cross-section. The cross-section upper limit obtained in this null or no observable effect experiment is ∼10⁴ times more sensitive than past experiments reporting positive results in ⁵⁴Mn.</div>

Segundo o Atlas Brasileiro de Energia Solar, apesar das diferentes características climáticas observadas no Brasil, pode-se constatar que a média anual de irradiação solar global apresenta boa uniformidade e elevados índices por todo o país. Os valores desta grandeza em quase toda a extensão do território brasileiro (4200-6700 Wh/m2/dia) são superiores aos da maioria dos países da União Europeia, como Alemanha (900-1250 Wh/m2/dia), França (900-1650 Wh/m2/dia) e Espanha (1200-1850 Wh/m2/dia), onde projetos para aproveitamento de energia solar, alguns contando com fortes incentivos governamentais, são amplamente disseminados. Grande parte dos avanços científicos obtidos nos estudos sobre aproveitamento da energia solar se deve à utilização de simuladores solares compactos nos experimentos de longa duração. Ao substituir o Sol por fontes artificiais, como lâmpadas capazes de emitir radiação próxima à solar, os simuladores eliminam a dependência de fatores naturais como condições climáticas, horário do dia, intermitência e movimento de direção da radiação solar. O projeto proposto para esta dissertação de Mestrado teve como objetivo o domínio do processo de concepção e fabricação de um simulador solar concentrador formado por lâmpadas e um refletor ótico. Uma vez dominada a técnica, um modelo piloto de simulador solar foi construído e alguns testes executados para avaliar a qualidade do projeto, a resistência dos componentes e o fator de concentração do aparato. / According to the Brazilian Atlas of Solar Energy, despite the different climatic characteristics observed in Brazil, the annual average of global solar irradiation has good uniformity and high levels throughout the country. The values of global solar irradiation in almost the entire length of Brazil (4200-6700 Wh/m2/day) are higher than those observed in most European Union countries, like Germany (900-1250 Wh/m2/day), France (900-1650 Wh/m2/day) and Spain (1200-1850 Wh/m2/day), where projects for solar energy applications, some of them relying on strong government incentives, are widely disseminated. Several scientific and technological advances made in the study of solar energy applications are due to the use of compact solar simulators in long-term experiments. Replacing the Sun by artificial sources, such as arc lamps with radiation emission similar to the Sun spectrum, indoor simulators avoid the dependence on natural conditions such as the weather, the daytime, the sunlight intermittence and the directional change of the solar radiation. The project proposed for this dissertation aimed to master the design and manufacturing processes of a high-flux solar simulator consisting of arc lamps and an optical reflector. Once technique was understood, a solar simulation pilot model was built and some tests were performed to assess the project quality, the resistance of components and the apparatus concentration factor.

No description available.

From the Proceedings of the 1974 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 19-20, 1974, Flagstaff, Arizona / The process of salt replacement desalination proposed is believed to be able to produce vast quantities of fresh water be desalination. This method, which is a novel approach to minimizing the costs of saline water conversion, consists of the substitution of solutes in a solution to be desalted by a replacer chemical, and the low energy removal of that replacer chemical. The ultrafiltration of larger molecular sized replacer chemicals with high flux membranes increases the produce yield rate and reduces the corresponding energy requirement, with respect to reverse osmosis. In addition, the initial captial investment is less since no pressure constraining devices are required. The alteration of the osmotic pressure of the replacer solution within the process can also take advantage of energy savings through the utilization of an easily reversible reaction which synthesizes and breaks down a constituent that has a significant osmotic pressure difference between phases. Finally, the unusual process of fixed gel syneresis shows potential as a low energy salt replacement type process, but still requires extensive investigation.

Volume overload is a common feature in patients on haemodialysis (HD). This contributes significantly to the cardiovascular disease burden seen in these patients. Clinical assessments of the volume state are often inaccurate. Techniques such as interdialytic blood pressure, relative blood volume monitoring, bioimpedance are available to improve clinical effectives. However all these techniques exhibit significant shortcomings in their accuracy, reliability and applicability at the bed side. We evaluated the usefulness of a dual compartment monitoring technique using Continuous Segmental Bioimpedance Spectroscopy (CSBIS) and Relative Blood Volume (RBV) as a tool to assess hydration status and determine dry weight. We also sought to evaluate the role of Atrial Natriuretic Peptide (ANP) and B-type Natriuretic Peptide (BNP) as a volume marker in dialysis patients. The Retrospective analysis of a historical cohort (n = 376, 55 Diabetic) showed a significant reduction in post-dialysis weights in the first three months of dialysis (72.5 to 70kg, p<0.027) with a non-significant increase in weight between months 6-12. The use of anti-hypertensive agents reduced insignificantly in the first 3 months, increased marginally between months 3-6 and significantly increased over the subsequent 6 months. The residual urea clearance (KRU) fell and dialysis times increased. The cohort was very different to that dialysing at Tassin and showed a dissociation between weight reduction and BP control. This may relate to occult volume overload. CSBIS-RBV monitoring in 9 patients with pulse ultrafiltration (pulse UF) showed distinct reproducible patterns relating to extra cellular fluid (ECF) and RBV rebound. An empirical Refill Ratio was then used to define the patterns of change and this was related to the state of their hydration. A value closer to unity was consistent with the attainment of best achievable target weight. The refill ratio fell significantly between the first (earlier) and third (last) rebound phase (1.97 ± 0.92 vs 1.32 ± 0.2). CSBIS monitoring was then carried out in 31 subjects, whilst varying dialysate composition, temperature and patient posture to analyse the effects of these changes on the ECF trace and to ascertain whether any of these interventions can trigger a change in the slope of the ECF trace distinct to that caused by UF. Only, isovolemic HD caused a change in both RBV and ECF in some patients that was explained by volume re-distribution due to gravitational shifts, poor vascular reactivity, sodium gradient between plasma and dialysate and the use of vasodilating antihypertensive agents. This has not been described previously. These will need to be explored further. The study did demonstrate a significant lack of comparability of absolute values of RECF between dialysis sessions even in the same patient. This too has not been described previously. This is likely to be due to subtle changes in fluid distribution between compartments. Therefore a relative changes must be studied. This sensitivity to subtle changes may increase the usefulness of the technique for ECF tracking through dialysis. The potential of dual compartment monitoring to track volume changes in real time was further explored in 29 patients of whom 21 achieved weight reductions and were able to be restudied. The Refill Ratio decreased significantly in the 21 patients who had their dry weights reduced by 0.95 ± 1.13 kg (1.41 ± 0.25 vs 1.25 ± 0.31). Blood pressure changes did not reach statistical significance. The technique was then used to examine differences in vascular refill between a 36oC and isothermic dialysis session in 20 stable prevalent patients. Pulse UF was carried out in both these sessions. There were no significant differences in Refill Ratios, energy removed and blood pressure response between the two sessions. The core temperature (CT) of these patients was close to 36oC and administering isothermic HD did not confer any additional benefit. Mean BNP levels in 12 patients during isovolemic HD and HD with UF did not relate to volume changes. ANP concentrations fell during a dialysis session in 11 patients from a mean 249 ± 143 pg/ml (mean ± SD) at the start of dialysis to 77 ± 65 pg/ml at the end of the session (p<0.001). During isolated UF levels did not change but fell in the ensuing sham phase indicating a time lag between volume loss and decreased generation. (136±99 pg/ml to 101±77.2 pg/ml; p<0.02) In a subsequent study ANP concentrations were measured throughout dialysis and in the post-HD period for 2 hours. A rebound in ANP concentration was observed occurring at around 90 min post-HD. The degree of this rebound may reflect the prevailing fluid state and merit further study. We have shown the utility of dual compartment monitoring with CSBIS-RBV technique and its potential in assessing volume changes in real time in haemodialysis patients. We have also shown the potential of ANP as an independent marker of volume status in the same setting. Both these techniques merit further study.