Constant Room Temperature Research Articles

Exergy analysis of building integrated semitransparent photovoltaic thermal (BiSPVT) system

In this paper, an exergy analysis of building integrated semitransparent photovoltaic thermal (BiSPVT) system has been carried out. In the proposed system, the room below building integrated semitransparent photovoltaic thermal system has been considered as an air-conditioned (constant room temperature). Energy balance equation for each components namely semitransparent photovoltaic roof, floor and room air have been given. Based on energy balance, an analytical expression for room air, solar cell and room floor temperatures have been derived along with solar cell electrical efficiency. Further by considering the day lighting parameters, an overall exergy of the proposed system has been derived for different number of air change between the room and ambient air. It has been observed that there is reduction in room air and solar cell temperatures with an increase of number of air changes. However, solar cell electrical efficiency increases with decrease in temperature of solar cell. Further, it is found that an electrical power and illumination inside the room are more dominating in comparison with thermal exergy. An increase of 1.15% in an overall exergy is observed for the number of air changes varies from 0 to 4. Experimental validation of theoretical model has also been carried out.

How to Switch Spin-Crossover Metal Complexes at Constant Room Temperature.

Spin-crossover metal complexes represent a highly promising class of molecular switches, the diverse physicochemical properties of which can be reversibly changed by different physical and chemical stimuli. One of the most interesting and examined features of these materials is the change of magnetic properties by changing the temperature or by irradiation with light at low temperatures. However, most prospective applications of such complexes require functioning at room temperature. This Concept article provides an overview about how the switching of spin-crossover metal complexes can be achieved at constant room temperature. The principles of switching by different physical and chemical methods in solution and in the solid state are presented in an easy-to-read form for nonspecialists. These are further supported and clarified by examples from the literature. The overview might also be interesting for experts that target spin-crossover systems functioning at ambient conditions.

Three-level experimental approach for creep and shrinkage of high-strength high-performance concrete

Most of the existing prediction models for creep and shrinkage are established based on the statistical regression analysis of test data drawn mostly from experiments performed on normal-strength concrete, and they might not be as applicable to high-strength high-performance concrete. The prediction precision can be improved by carrying out on the given concrete short-term creep and shrinkage measurements. A three-level experimental approach for creep and shrinkage is proposed in this study. Take the high-strength high-performance concrete used in the auxiliary shipping channel bridge of Sutong Bridge for example, the detailed three-level experimental process and results were presented. The specimens were grouped on three levels: “Material level”, “Component level” and “Structural level”. On the first level, plain concrete specimens were experimented in a constant temperature and constant humidity room. On the second level, creep and shrinkage of reinforced concrete specimens with different reinforcement ratio were experimented. On the third level, the long-term behavior of a segmental concrete cantilever beam, 12.8m long, under natural environment which was close to that of the actual bridge was studied. This experimental approach can provide a new train of thought to improve the predicted precision of the creep and shrinkage effects of the long-span concrete structures.

ENHANCEMENT OF GREEN ALGAE HYDROGEN PRODUCTION BY LASER IRRADIATION

Biohydrogen is an alternative to support the increasing hydrogen demand in the future. Biohydrogen is hydrogen gas produced by green algae and bacteria in certain quantity. The aim of this research is to enhance hydrogen gas production by green algae (Closterium sp.) using laser light. The laser used in this experiment was a diode laser operating in continuous mode with wavelength of 655 nm. Green algae are placed in a sulphur deprived medium so it will produce hydrogen gas. This algae is irradiated with diode laser for 30 minutes then stop before continue for the next 30 minutes. This process is repeated until the total irradiation is 120 minutes. Both strains of green algae are set up into measuring system under exposure of sunlight in a constant room temperature. The volume and rate of hydrogen gas produced is examined by measuring the dye position in capillary tube of 0.5 mm radius. The results showed that there is a 9.0% increase of hydrogen gas production in radiated strain of green algae compared to the wild strain. The rate of hydrogen gas production of radiated algae is faster than the wild strain. This showed that, red light laser has absorbed cell green algae and mutated its behaviour for producing more hydrogen gas. This result is in good agreement with other researcher.

Study on corrosion resistance of high - entropy alloy in medium acid liquid and chemical properties

High-entropy alloy is a new alloy which is different from traditional alloys. The high entropy alloys were started in Tsing Hua University of Taiwan since 1995 by Yeh et al. Consisting of a variety of elements, each element occupying a similar compared with other alloy elements to form a high entropy. We could define high entropy alloys as having approximately equal concentrations, made up of a group of 5 to 11 major elements. In general, the content of each element is not more than 35% by weight of the alloy. During the investigation it turned out that this alloy has a high hardness and is also corrosion proof and also strength and good thermal stability. In the experimental area, scientists used different tools, including traditional casting, mechanical alloying, sputtering, splat-quenching to obtain the high entropy alloys with different alloying elements and then to investigate the corresponding microstructures and mechanical, chemical, thermal, and electronic performances. The present study is aimed to investigate the corrosion resistance in a different medium acid and try to put in evidence the mechanical properties. Forasmuch of the wide composition range and the enormous number of alloy systems in high entropy alloys, the mechanical properties of high entropy alloys can vary significantly. In terms of hardness, the most critical factors are: hardness/strength of each composing phase in the alloy, distribution of the composing phases. The corrosion resistance of an high entropy alloy was made in acid liquid such as 10%HNO3-3%HF, 10%H2SO4, 5%HCl and then was investigated, respectively with weight loss experiment. Weight loss test was carried out by put the samples into the acid solution for corrosion. The solution was maintained at a constant room temperature. The liquid formulations used for tests were 3% hydrofluoric acid with 10% nitric acid, 10% sulphuric acid, 5% hydrochloric acid. Weight loss of the samples was measured by electronic scale.

STANDARDIZATION OF GERMINATION TEST AND RESPONSE TO NACL SALT STRESS IN Toona cliliata SEEDS

AbstractThe objective of this study was to evaluate the germination of Australian cedar seeds (Toona ciliata M. Roem) in three different substrates and two photoperiods and evaluate the effect of salt stress with sodium chloride (NaCl) on the viability and vigor of seeds, conducting two experiments. The first experiment was conducted in a constant temperature room at 25 C and two light regimes 12h 24h white light; and three substrates: sand, between paper and on paper. Evaluations were performed on the seventhand twenty-first day after sowing. Results were expressed as percentage of Normal Seedlings, Abnormal Seedlings and Dead Seeds, Number of True Leaves, Fresh, Dry Matter, Seedling Length and Root. The second experiment used constant 25 C and photoperiod of 12 hours light. With treatments T1 (0mM: distilled water); 25mMNaCl T2; T3 50mMNaCl; T4 and T5 100mMNaCl 75mMNaCl. We evaluated PCG, G, IVG, CP, CR. The photoperiod of 24h light, does not influence the final seed germination and the use of paper on substrate provided the highest percentage of germinated seeds. As to the effect of salt stress, the concentration of 50mMsalt, caused damage to the development of seedlings.ResumoPadronização do teste de germinação e resposta ao estresse salino por NaCl em sementes de Toona ciliata. O objetivo do trabalho foi avaliar a germinação de sementes de cedro australiano (Toona ciliata M. Roem) em três substratos com dois fotoperíodos e avaliar o efeito do estresse salino com cloreto de sódio (NaCl) na viabilidade e vigor de sementes. O experimento I foi conduzido em ambiente com temperatura constante a 25 ºC e dois regimes de luminosidade, 12h de 24h de luz branca; três substratos: areia, entre papel e sobre papel. As avaliações foram realizadas no sétimo e vigésimo primeiro dia após a semeadura. Os resultados expressos em porcentagem de Plântulas Normais, Plântulas Anormais e Sementes Mortas, número de Folhas Verdadeiras, Massa Fresca, Massa Seca, Comprimento de Plântula e Raiz. O experimento II utilizou temperatura constante a 25 ºC e fotoperíodo de 12 horas luz. Com os tratamentos T1 (0 mM: água destilada); T2 25 mMNaCl; T3 50 mMNaCl; T4 75 mMNaCl e T5 100 mMNaCl. Avaliando-se PCG, G, IVG, CP e CR. O fotoperíodo de 24h de luz, não influencia na germinação e o uso do substrato sobre papel proporcionou a maior germinação. Quanto ao efeito do estresse salino, a concentração de 20 mM de sal, prejudicou o desenvolvimento das plântulas.Palavras-chave: Sementes florestais; análise de sementes, vigor, salinidade.

A simplified mathematical model for transient simulation of thermal performance and energy assessment for active facades

The extended use of double skin façade (DSF) in different kinds of buildings imposes HVAC (Heating Ventilation Air Conditioning) designers to use quick and accurate software to help in taking the right decisions related to energy consumption and thermal comfort. The lack of such methods was the motive to present this paper. Validation of a simplified mathematical model for dynamic simulation of the thermal performance of DSF was presented by comparing results with another detailed simulation model DIGITHON, for a complete year. Moreover the mathematical model was developed to calculate thermal energy due to convection losses from outer facade layer, solar gains and internal loads. A more detailed comparison of energy consumption at different climatic conditions of four cities in Europe has been shown. Implementation of the simplified model in thermo-active-building-system-(TABS) also was illustrated, and how such a model could be useful in one of four methods mentioned in standard ISO-11885-4 to predict heat transfer on TABS. This particular method needs the solar gains and losses due to transmission determined with a constant room temperature by another software which the mathematical model could be implemented in.

Effects of Temperature, Humidity and Air Flow on Fungal Growth Rate on Loaded Ventilation Filters

This study compares the fungal growth ratio on loaded ventilation filters under various temperature, relative humidity (RH), and air flow conditions in a controlled laboratory setting. A new full-size commercial building ventilation filter was loaded with malt extract nutrients and conidia of Cladosporium sphaerospermum in an ASHRAE Standard 52.2 filter test facility. Small sections cut from this filter were incubated under the following conditions: constant room temperature and a high RH of 97%; sinusoidal temperature (with an amplitude of 10°C, an average of 23°C, and a period of 24 hr) and a mean RH of 97%; room temperature and step changes between 97% and 75% RH, 97% and 43% RH, and 97% and 11% RH every 12 hr. The biomass on the filter sections was measured using both an elution–culture method and by ergosterol assay immediately after loading and every 2 days up to 10 days after loading. Fungal growth was detected earlier using ergosterol content than with the elution–culture method. A student's t-test indicated that Cladosporium sphaerospermum grew better at the constant room temperature condition than at the sinusoidal temperature condition. By part-time exposure to dry environments, the fungal growth was reduced (75% and 43% RH) or even inhibited (11% RH). Additional loaded filters were installed in the wind tunnel at room temperature and an RH greater than 95% under one of two air flow test conditions: continuous air flow or air flow only 9 hr/day with a flow rate of 0.7 m3/s (filter media velocity 0.15 m/s). Swab tests and a tease mount method were used to detect fungal growth on the filters at day 0, 5, and 10. Fungal growth was detected for both test conditions, which indicates that when temperature and relative humidity are optimum, controlling the air flow alone cannot prevent fungal growth. In real applications where nutrients are less sufficient than in this laboratory study, fungal growth rate may be reduced under the same operating conditions.

A Fiber Bragg grating based tilt sensor suitable for constant temperature room

Constant-temperature rooms have been widely used in industrial production, quality testing, and research laboratories. This paper proposes a high-precision tilt sensor suitable for a constant- temperature room, which has achieved a wide-range power change while the fiber Bragg grating (FBG) reflection peak wavelength shifted very little, thereby demonstrating a novel method for obtaining a high-precision tilt sensor. This paper also studies the effect of the reflection peak on measurement precision. The proposed sensor can distinguish the direction of tilt with an excellent sensitivity of 403 dBm/° and a highest achievable resolution of 2.481 × 10−5 ° (that is, 0.08% of the measuring range).

Parametric study to determine the effect of temperature on oil solidifier performance and the development of a new empirical correlation for predicting effectiveness

Temperature can play a significant role in the efficacy of solidifiers in removing oil slicks on water. We studied and quantified the effect of temperature on the performance of several solidifiers using 5 different types of oils under a newly developed testing protocol by conducting experiments in constant temperature rooms set at 22°C and 5°C. The results indicated that solidifier efficiency decreased substantially at the lower temperature, especially at lower application rates. The removal efficiency of the solidifier was in general directly proportional to temperature, except for the heavier oils, where removal by attachment was observed. Solidifier products with lower powder bulk density exhibited the best removal effectiveness. Analysis of experimental data yielded empirical correlations involving certain operational variables such as application rate, temperature, solidifier property (bulk density), and oil property (viscosity). Regression analysis was used to fit a mathematical model to the experimental solidifier effectiveness data.

Kinetic study on removal of heavy metal ions from aqueous solution by using soil.

In the present study, the feasibility of soil used as a low-cost adsorbent for the removal of Cu(2+), Zn(2+), and Pb(2+) ions from aqueous solution was investigated. The kinetics for adsorption of the heavy metal ions from aqueous solution by soil was examined under batch mode. The influence of the contact time and initial concentration for the adsorption process at pH of 4.5, under a constant room temperature of 25 ± 1°C were studied. The adsorption capacity of the three heavy metal ions from aqueous solution was decreased in order of Pb(2+) > Cu(2+) > Zn(2+). The soil was characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopic-energy dispersive X-ray (SEM-EDX), and Brunauer, Emmett, and Teller (BET) surface area analyzer. From the FTIR analysis, the experimental data was corresponded to the peak changes of the spectra obtained before and after adsorption process. Studies on SEM-EDX showed distinct adsorption of the heavy metal ions and the mineral composition in the study areas were determined to be silica (SiO2), alumina (Al2O3), and iron(III) oxide (FeO3). A distinct decrease of the specific surface area and total pore volumes of the soil after adsorption was found from the BET analysis. The experimental results obtained were analyzed using four adsorption kinetic models, namely pseudo-first-order, pseudo-second-order, Elovich, and intraparticle diffusion. Evaluating the linear correlation coefficients, the kinetic studies showed that pseudo-second-order equation described the data appropriable than others. It was concluded that soil can be used as an effective adsorbent for removing Cu(2+), Zn(2+), and Pb(2+) ions from aqueous solution.

Data mining of space heating system performance in affordable housing

The space heating in residential buildings accounts for a considerable amount of the primary energy use. Therefore, understanding the operation and performance of space heating systems becomes crucial in improving occupant comfort while reducing energy use. This study investigated the behavior of occupants adjusting their thermostat settings and heating system operations in a 62-unit affordable housing complex in Revere, Massachusetts, USA. The data mining methods, including clustering approach and decision trees, were used to ascertain occupant behavior patterns. Data tabulating ON/OFF space heating states was assessed, to provide a better understanding of the intermittent operation of space heating systems in terms of system cycling frequency and the duration of each operation. The decision tree was used to verify the link between room temperature settings, house and heating system characteristics and the heating energy use. The results suggest that the majority of apartments show fairly constant room temperature profiles with limited variations during a day or between weekday and weekend. Data clustering results revealed six typical patterns of room temperature profiles during the heating season. Space heating systems cycled more frequently than anticipated due to a tight range of room thermostat settings and potentially oversized heating capacities. The results from this study affirm data mining techniques are an effective method to analyze large datasets and extract hidden patterns to inform design and improve operations.

Ionization controls for biomineralization-inspired CO2 chemical looping at constant room temperature.

Living organisms such as corals can carry out CO2 looping efficiently via biomineralization under ambient conditions. Inspired by this natural process, we establish a solution system of calcium acetate-ethanol-water (Ca(Ac)2-C2H5OH-H2O) for CO2 chemical looping at constant room temperature. The CO2 capture is achieved by its reaction with Ca(Ac)2 to form calcium carbonate (CaCO3) mineral and HAc in the binary solvent with a high C2H5OH content. However, an increase in the H2O content in the system triggers acetic acid (HAc)-induced CaCO3 dissolution to release CO2. The system can be recovered for CO2 capture readily by the replenishment of C2H5OH. This biomimetic mineralization-based CO2 capture/release is controlled by the ionization states of the electrolytes, and is precisely regulated in the C2H5OH-H2O binary solvent. Our attempt highlights the fundamental principle of solution chemistry in reaction control and provides a bioinspired strategy for CO2 capture/release with very low cost and easy availability.

Tribo-sustainability issues in recycled aluminium

In the present paper, adding a small amount of magnesium (Mg) content on the dry sliding wear behaviour for recycled aluminium has been reported. Recycled aluminium composition, normal pressures and sliding distances on recycled aluminium at constant room temperature was also studied. The cast alloys and worn surfaces were characterised by SEM/EDX microanalysis and hardness test. The results indicate that, the wear rate of recycled aluminium increases with an increase in normal pressures and sliding distances in all the cases and decreases with 0.7wt.% Mg added to the recycled aluminium. This is due to the modification and solid solution strengthening and precipitation hardening. The worn surface study indicates that the formation of iron-rich oxide layer between the mating surfaces during sliding, improves sliding wear performance as the EDAX results show a reduction of ferrous content from abraded surfaces by more than 60%.

Chemical Modifications and Diatom Community Development on Volcanic Clayey Sediments During an Indoor Maturation Experiment

Maturation experiments of volcanic mud samples with mineral water were followed up during 120 days at constant room temperature (20ºC) to track geochemical modifications induced by the process and, eventually, the development of diatom communities. Different abiotic conditions were tested during the experiments. Mud samples were collected in Azores and Madeira Archipelagos (Portugal) and the biological inoculum was collected from the edge of a fumarole from Azores (Portugal). The assemblages of diatoms were dominated by Nitzschia species both in the inoculum and on maturated muds. Although one of the samples from São Miguel island (Azores) was dominated by Nitzschia cf. thermalis var. minor, the mud sample from Porto Santo (Madeira) allowed the development mainly of Nitzschia communis during maturation experiments. Associations between chemical composition and samples’ mineralogical signature were established by cluster analysis. Slight enrichment on Na+ and Ca2+ was detected in samples after maturation and exchangeable cations content was improved by the process. This research includes a multidisciplinary approach that contributes to the understanding of interactions between volcanic substrates and specific diatom species and geochemical modifications induced by maturation in volcanic materials.

Synthesis and Characterization of CuO Nanotubes (NTs) Formed By Anodization Sonoelectrochemical

The CuO is an important semiconductor material because this presents a narrow bandgap value (~1.2 – 1.7 eV), p-type conductivity, low toxicity and abundance in nature. From comparison of the photoelectrochemical behavior between CuO and others semiconductor, it is concluded that this oxide is sensible to visible radiation whereas others, more widely used such as; TiO2, ZnO, which absorb in UV region.Despite the above, the copper oxide has a low diffusion rate of charge carriers. Therefore, new synthesis routes leading to a nanostructured oxide is required, so that the photogenerated electrons are accumulated in the vicinity of the surface. This is to facilitate the transfer process of charge per on the recombination.This report shows the results concerning the preparation sonoelectrochemical of CuO nanotubes (NTs). Synthesis of CuO NTs is carried out on a copper (Cu) foil in organic media (x% water in ethylene glycol + 0.5 wt % CuC2O4) using the electrochemical anodization method at a constant room temperature. The anodization is carried out for 10 min at an applied potential of 25 V. Cu foil acts as anode and electrode of carbon (C) acts as cathode. The anodized samples are properly washed with distilled water, to remove the occluded ions, and dried in a furnace.The CuO NTs were characterized by sweep electronic microscopy (SEM), energy dispersive X-ray analysis (EDXA) and Raman spectroscopy.The micrographs show an array of nanotubes on the substrate. The composition of the nanotubes immediately formed consisted mainly of copper, when the synthesis was conducted in a solution with a higher % of water. However, when the samples were heat treated in oxygen atmosphere, an array of CuO NTs was obtained.Furthermore, these samples were characterized by Photoelectrochemical Studies. Acknowledgment The financial support of Fondecyt-Chile (Project N° 1140963) and DI-PUCV (Projects N° 037.305/2013) is gratefully acknowledged by the authors.

Performance enhancement of PEMC liquid level sensor subjected to environmental temperature variation

In this paper, the performance of a resonant Piezoelectric-excited Millimeter-sized Cantilever (PEMC) used as liquid level sensor has been studied. The sensitivity of this sensor affected by environmental temperature variation is investigated via theoretical and Finite Element Models (FEM). In order to validate this FEM, first, simulation results are compared with the theoretical and experimental ones for a sensor operating at constant room temperature. The simulation results are in a good agreement with experimental ones. Then, proposed theoretical model and FEM are used to study the dynamic behavior of the device when the environmental temperature is changed. The results indicate that although natural frequencies of sensor change due to temperature variation, the resultant shift remains almost the same regardless of specific immersion depths. Also, it can be concluded that temperature variation of about 50 °C affects the liquid level measurement accuracy up to 29 μm which is significant compared to a minimum detectable liquid level change of about 8 μm by this sensor reported previously in literature.

Synthesis of ZrO2 nanotubes in inorganic and organic electrolytes by anodic oxidation of zirconium

Present work reports on the results of the electrochemical growth of self-ordered zirconia nanotubes formed in aqueous Na2SO4 + HF and nonaqueous electrolytes with glycerol addition. Anodization process was carried out in this inorganic water-based mixture with constant pH = 2.5 and in the voltage range from 5 to 60 V. Similar experiments were repeated in an organic glycerol-based electrolyte with the voltage equal to 20 V and with variable glycerol concentration. All experiments were conducted at constant room temperature. The tube diameter dependence on the voltage of anodization process in an inorganic electrolyte was derived. It was found that when glycerol addition to water electrolyte was used, it takes more time to produce long zirconia nanotubes. However, they do not collapse as the similar structure of the same length formed in aqueous electrolyte.

Development of Spectral Delayed Luminescence System for Whole Saliva Analysis: A Prototype Study

This paperwork presents the development of spectral delayed luminescence system for the measurement of whole saliva. Despite various reports of delayed luminescence and its correlation to various diseases, it has fail to highlight the specific cause of the occurrence suggesting it being more suitable as a screening tool utilizing saliva as non-invasive sampling medium. Therefore it is the aim of this paper to have the system critical performance tested before putting it to use at the field. The system prototype is tested for its response during room temperature operation and during spot cooling of the photomultiplier tube module. Delayed luminescence of saliva is compared over distilled water as a control. The spectral delayed luminescence of saliva is compared to that of the dimmed white light for functional testing purposes. Through experiments, the best operation for the system is at constant room temperature with light stimulation time determined at 150 ms. Being 98% water, the delayed luminescence of saliva is slightly greater than that of distilled water. Given light stimulation of wide spectrum from white LED, the delayed luminescence of saliva is accumulated between 495 nm and 530 nm. Results demonstrated that the system for spectral delayed luminescence of saliva is viable and capable for acquiring data for further studies.

Mechanical Properties of Composite Mortars Using Flurogypsum and PVC Particles

The present work describes the viability of a mortar binder based on two industrial by-products: poly(vinyl chloride) (PVC) particles from scrap and anhydrite (CaSO4) from fluorgypsum. Mortar composites were made incorporating different amounts of PVC particles and cured at constant room temperature during various periods of time. From X-ray diffraction, it was possible to follow the hydration process and to estimate the effect of the PVC particles on anhydrite transformation to gypsum (CaSO4·2H2O). Compressive strength from uniaxial testing was measured from stress-strain curves carried out at room temperature. According to these results, the hydration rates of the composites depend on the concentration of PVC particles and there is an enhancement in their compressive strength as particle content increases, reaching values of 36 MPa after 28 days.