Temperature Recovery Research Articles

A Simplified Design Process for Thermal Supplementation of a Medium Sized Aquaponics System to Ensure Sustainability

Growing climate change awareness incentivizes establishment and implementation of efficient alternative food production methodologies such as aquaponics, with potentially high yield versus reduced footprint, urban implementation and local food security and employment. Viably maintaining such systems during freezing winter climate necessitates thermal supplementation to maintain biological viability of the fish stock and bio-filter micro-organisms. The purpose of this study is to present a simplified baseline approach for determining thermal supplementation for establishing sustainability of a medium sized aquaponics system. An existing aquaponics system is examined and described through historical temperature data, system thermal interaction via mass-flow loop energy transfer and a physical layout. Applicable historical measurements for initial supplementation determination are be listed. The chosen solar supplementation source is discussed in terms of cost and energy input. Further examination of study data informs system energy interaction and system micro-biota viability. The presented method results in an inter-cold-front positive system temperature recovery slope of 0.278˚C per day and an extrapolated temperature buffer recovery in 15 days, validating the viability of the method as presented. The value of adopting this method lies in promoting aquaponics system adoption by simplifying system-viability supplementation estimation where direct grid energy unit-cost comparison allows for informed decisions. Adopting the method for the Bloemfontein area, or locations with similar climate, is thus recommended.

Down-dip circulation at the united downs deep geothermal power project maximizes heat recovery and minimizes seismicity

Fault damage zones potentially represent native permeable channels within otherwise ultra-tight igneous formations that may be used to promote fluid circulation for convective heat recovery. The United Downs Deep Geothermal Power (UDDGP) project aims to recover geothermal energy by directly injecting, circulating then recovering fluids from such a fault. The UDDGP project injects fluid into the fault at 2500 m where rock temperature is ~75 °C – 80 °C and recovers the injectate from 4500 m, where the bottom hole temperature is predicted to be 190 °C. We explore such down-dip circulation through numerical modeling to determine the anticipated temperature and longevity of the thermal recovery and the potential for induced seismicity (fault reactivation) by contrasting response for up-dip circulation. The results reveal that down-dip circulation not only maximizes water temperature and flow rate at the outlet but also simultaneously suppresses fault reactivation over the long term. In down-dip circulation, fault permeability in the critically stressed shallow fault damage zone is more greatly enhanced than that of the deep fault as a result of the strong injection-induced thermal stress. Fault sealing is breached as a result of reactivation in the shallow fault, prompting transverse fluid penetration and subsequent fluid circulation in the footwall. Switching the injection scheme from down-dip circulation to up-dip circulation, while maintaining an identical injection rate, leads to a drastic increase in the cumulative number of seismic events, with the average magnitude increasing from 1 to 2. This reversed well configuration (circulation bottom to top) also reduces power output from 6 to 7 MWthermal to 2 MWthermal, due to reduced enthalpy and flow rate in the production well. The outcomes from this study confirm the preferred design of the well pattern as circulating top to bottom, to both maximize heat recovery and limit induced seismicity. A lower production pressure is necessary to avoid pressure build-up inside the fault . Production pressure at 15–20 MPa could ensure both high cumulative power generation and a stable fault state.

Thermographic Analysis of the Metacarpal and Metatarsal Areas in Jumping Sport Horses and Leisure Horses in Response to Warm-Up Duration.

Simple SummaryA warm-up prepares the body for effort by improving blood supply to muscles and increasing the flexibility of joints, ligaments, and tendons. Warm-up is considered as a necessary preliminary step of each training session. This study assessed the impact of different regimes of warm-up on the surface temperature of the distal parts of limbs in horses used for jumping and leisure riding. Six showjumping horses and six leisure horses were included in the study. The studied horses were warmed up by walking and trotting for various time periods. The rectal temperature and body surface temperature of the distal parts of the four limbs were measured before warm-up, just after it, and during recovery. The warm-up-induced increase in analysed temperatures was higher in jumping sport horses than in leisure horses.This study aimed to assess the impact of various types of warm-up on the metacarpal and metatarsal surface temperature in jumping sport horses in comparison to leisure horses, which work usually less intensively. Six clinically healthy sport geldings, contestants in showjumping competitions, and six geldings used for leisure riding were included in the study. The experiment was conducted for four consecutive days, during which the horses were warmed up by walking and trotting for various durations. Images were taken with a FLUKE Ti9 thermal imager to determine the resting, post-effort, and recovery temperature of the dorsal and plantar surface of the metacarpus and metatarsus of the four limbs. The obtained data were analysed with SmartView 4.1. software. The increase of measured rectal and surface temperatures was proportional to the warm-up duration. The surface temperature increase in the distal limb parts in jumping sport horses was greater than in horses used for leisure. The plantar surface was also warmer than the dorsal surface of the metacarpal/metatarsal areas, with a forelimb being warmer than a hind limb. Elevated temperatures after warm-up persist for 30 min in the recovery period, especially in jumping sport horses compared to leisure horses. Thus, the warming up effect is achieved earlier and lasts longer in heavily trained horses than in non-performance horses.

Methodology for the food preservation assessment of residential refrigerators: Compressor and consumer practices effects on absolute and relative preservation indicators

Predictive microbiology models and 2.8E6 ham temperature measurements quantified absolute (API) and relative preservation indicators (RPI) assessing the performance of a residential refrigerator operating at 5 °C, the conventional setting for energy use assessments. Factors considered were compressor (single/variable speed, SS/VS), ambient temperature (21.1/32.2 °C), food load (22.5/39 kg), doors (closed/opening cycles), and fixed/movable samples (simulating breakfast use). APIT(t) based on 48 h temperature-dependent Listeria monocytogenes exponential growth ranged 0.23–0.36 log CFU/g at 32.2 °C/VS for all sample types and loads. The API value at the recommended 5 °C for ham (API5 °C, 0.155 log CFU/g) defined RPI = APIT(t)/API5 °C with values <1, ~1, >1 indicating a better, similar or worse preservation than constant 5 °C storage. The highest RPI value (2.32) was observed for VS/32.2 °C/high load/movable samples; however, it reached 1.10 when the entire ham temperature profile was lowered by 3.7 °C, the maximum possible without risking product freezing. A probabilistic analysis considering the variability of predictive microbiology parameters and temperature measurements, yielded high 95% percentile RPI values for all conditions. Although the SS compressor showed better RPIs, operating strategies for all compressor types should be modified to ensure lower-temperatures and shorter temperature recovery times while still meeting energy use regulations. The higher energy efficiency and multiple adjustments possible of VS compressors suggest that they should deliver better food preservation than SS compressors. This study showed an effective use of product temperature to assess the preservation performance of all cold chain components.

Sponge-like Ca-alginate/Lix-84 beads for selective separation of Mo(VI) from some rare earth elements

In this investigation, a novel alginate complex was developed for the selective separation of molybdenum (Mo(VI)) ions from some rare earth elements (REEs). In this regard, alginate as a natural polysaccharide was impregnated and modified with 2-hydroxy-5-nonylacetophenone oxime (Lix-84) and characterized using FT-IR, TGA/DTA and SEM-EDX. The relation between medium acidity, adsorption kinetics, sorbent dose, isotherm models, temperature and Mo(VI) recovery was investigated. It was concluded that the impregnation stage promoted the Mo(VI) separation. The kinetics and isotherm data were well-fitted and matched with the pseudo-first-order model and Langmuir isotherm model; respectively. The Langmuir maximum adsorption capacity of Mo(VI) reached 72.2 mg/g. The developed material showed excellent separation performance towards Mo ions over the investigated REEs. The desorption and recovery of the loaded Mo(VI) ions were achieved using 1.0 M HCl. Reutilization of Alg/Lix-84 was confirmed up to three adsorption–desorption cycles with no damage of the beads as proved with SEM analysis. The adsorption mechanism of molybdenum onto Alg/Lix-84 was elucidated through FTIR and XPS measurements and was found to be governed by both electrostatic interaction and ion exchange. Therefore, the developed material has a promising potential for the selective separation of molybdenum from REEs-containing solution.

Multi-performance shape memory epoxy resins and their composites with narrow transition temperature range

Shape memory epoxy resins are one of the most widely used engineering smart polymers, which is mainly used in active deformation structures in aerospace, intelligent bionics, and other fields. A series of shape memory epoxy resins with a narrow glass transition temperature range, strong inter-segment forces and uniform cross-linked networks were designed and synthesized in this study. By adjusting the stoichiometric ratio and cross-linking density, the length of the chain segment was controlled uniformly. The glass transition temperature range reached 14–23 °C, which improved the efficiency of shape memory action. In addition, the multi-amines crosslinking agents were used to adjust the distribution of the chain segment and achieve the effect of regulating the glass transition temperature (Tg). Moreover, the addition of epoxy-terminated liquid nitrile rubber (ETBN) composites enabled toughen of systems. The elongation at break could be increased by 4 times. Furthermore, Tg, modulus and strength of composites were improved by adding high-temperature latent hardener based on the ETBN toughening system combined with two-stage curing method. The composites with narrow transition temperature range were more suitable for shape fixation and recovery temperature with higher precision and closer spacing, which meet the higher requirements in aerospace field.

Effect of metal/metal oxide catalysts on graphene fiber for improved NO2 sensing

Noble metal/metal-oxide-based hybrid gas sensors exhibit a low operating temperature, remarkable sensitivity, and fast recovery. As additives, noble metals induce a catalytic sensitization effect, which promotes charge transfer from the metal oxide to the analyte molecules, the so-called spillover mechanism. This suggests that metal catalysts can improve gas sensing performance. Herein, for the first time, non-noble metals are introduced on hybrid metal oxide/graphene fibers as sensitizers to fabricate high-performance chemiresistive sensors. The formation of metal components can be effectively controlled by annealing the metal oxide on graphene. Remarkably, compared with the corresponding metal oxide/graphene fiber sensors without metal components, the metal/metal oxide/graphene fiber sensors exhibit over a 16-fold higher response to NO2 gas as well as effective recovery characteristics. Specifically, the Cu/Cu2O/graphene and Ni/NiO/graphene fiber sensors operating at 150 °C exhibit sensitivities of 18.90 % and 0.82 %, respectively, for 5 ppm NO2 gas. The proposed strategy to achieve flexible graphene fiber chemiresistors by decorating them with non-noble metal and metal oxide nanoparticles opens a new avenue for realizing high-performance devices, such as photovoltaic devices, photocatalysts, and chemical catalysts.

Estimation of casing material corrosion rates for supercritical geothermal development

Supercritical geothermal development method has been proposed to increase the use of geothermal resources; the associated challenges include high temperatures and pressures, as well as an acidic environment, which increase the corrosion rate of casing materials. Here, we estimated material corrosion rates assuming that the temperature and pressure in a developmental environment were 500 °C and 60 MPa, respectively. Wells WD-1a in the Kakkonda geothermal field, Japan, and Icelandic Deep Drilling Program-1 (IDDP-1) were used as model cases for the concentrations of volcanic gasses. Geochemical calculations were conducted to obtain distributions of pH values from room temperature to 500 °C at 60 MPa. Corrosion rate distributions for the metallic materials were derived for the temperature recovery period after drilling and production and post-production periods inside the well. Consequently, the pH remained approximately constant at temperatures ≤ 300 °C and increased as the temperature exceeded 300 °C. In the supercritical temperature and pressure region, the pH increased as the pressure decreased, and it maximized at a 0.35 g/cm3 fluid density. The IDDP-1 model exhibited lower pH values than the WD-1a model; the H2S/CO2 ratio and HCl gas also increased. Furthermore, from room temperature to 300 °C, the corrosion rates were found to increase with the temperature and maximized in the subcritical regions at 300–350 °C. The corrosion rates then decreased as the temperature increased in the supercritical temperature regions. In the possible developmental processes, the corrosion rates tended to be high at temperature of 300–350 °C (~2,000 m) during the temperature recovery period after drilling, whereas the corrosion rates tended to increase near the wellhead during fluid production. The corrosion rate maximized near the wellhead immediately after the production period ceased at a well depth of 1,000–1,500 m the following week.

Preparation of Dopamine Nanoparticles and Its Application in the Treatment of Neonatal Scleredema

The polydopamine (PDA) nanoparticles were prepared by the aqueous phase oxidation, and doxorubicin (DOX) was applied on surface of PDA under appropriate temperature and Pondus Hydrogenii (pH) conditions. The human umbilical vein-derived mesenchymal stem cells (hUV-MSCs) were sub-cultured, and then destroyed by lysing and freeze-thaw to obtain the stem cell membrane (SSM) fragments, which were squeezed using the polycarbonate porous membrane and then wrapped in the surfaces of the PDA nanoparticles by means of water bath ultrasound. In this way, the biomimetic nano medicine was synthesized. In the experiment, the DOX release amount of the nanomedicine under different conditions was analyzed. Under the precondition that the concentration of the drug was changed, and it was used to explore proliferation activity of human esophageal cancer cell (Eca-109). Mice with sclerosed skin caused by scleredema were selected as the test subjects to observe the inhibitory effect of the prepared drugs on its fibrosis. In addition, 90 cases of neonatal scleredema were selected and grouped to verify the improvement effect of nano-medicine injection on their symptoms. The results relaved that average particle size (APS) of synthesized drug was 77.6±8.5 nm, and the drug loading of DOX loaded on the surface of PDA was 18.4%. The transmission electron microscopy (TEM) displayed that surface of prepared drug was structured with cell membrane, and the release of DOX was correlated with the pH of the drug solution. Under the condition of a certain DOX concentration, the prepared nano-drug could kill the Eca-109 cells strongly (P &lt; 0.05). In the sclerosing phase, the skin thickness and collagen index of the mice could be reduced by injecting different doses of the drug solutions (P &lt; 0.05), while the content of transforming growth factor β (TGF-β)/platelet-derived growth factor A-chain (PDGFA) was decreased (P &lt; 0.05). The severity score of newborn children was greatly reduced after drug injection treatment; and the temperature recovery time, sclerosis disappearance time, and hospitalization time were shortened to a great extent (P &lt; 0.05).

Chill coma onset and recovery fail to reveal true variation in thermal performance among populations of Drosophila melanogaster

Species from colder climates tend to be more chill tolerant regardless of the chill tolerance trait measured, but for Drosophila melanogaster, population-level differences in chill tolerance among populations are not always found when a single trait is measured in the laboratory. We measured chill coma onset temperature, chill coma recovery time, and survival after chronic cold exposure in replicate lines derived from multiple paired African and European D. melanogaster populations. The populations in our study were previously found to differ in chronic cold survival ability, which is believed to have evolved independently in each population pair; however, they did not differ in chill coma onset temperature and chill coma recovery time in a manner that reflected their geographic origins, even though these traits are known to vary with origin latitude among Drosophila species and are among the most common metrics of thermal tolerance in insects. While it is common practice to measure only one chill tolerance trait when comparing chill tolerance among insect populations, our results emphasise the importance of measuring more than one thermal tolerance trait to minimize the risk of missing real adaptive variation in insect thermal tolerance.

Biomass Shape Memory Elastomers with Rapid Self-Healing Properties and High Recyclability.

Biomass bifunctional polyamide elastomers (BbPEs) were successfully prepared from dimer acid (DA), trimer acid (TA), and triethylenetetramine with shape memory and self-healing abilities. In the composition structure of BbPEs, vast hydrogen bonds formed among the amide bonds of different segments endowed the BbPEs with self-healing ability. At room temperature, the mechanical properties of BbPEs can be restored to 49% of the original condition after healing for 2 h. In addition, the physical and chemical cross-linking endowed the BbPE with preferable mechanical and shape memory properties. The tensile strength of the material is 4.4 ± 0.1 MPa, and the elongation at break reaches 1500 ± 2%. Under the recovery temperature of 60 °C, the shape memory recovery rate of 5 min can reach 95%. The recovery efficiency is 88.9%. This material can be utilized for many practical applications, such as intelligent electronic devices, bionic materials, and so on.

Effects of Amorphous Poly Alpha Olefin (APAO) and Polyphosphoric Acid (PPA) on the Rheological Properties, Compatibility and Stability of Asphalt Binder

High production costs and poor storage stability have become important constraints in the manufacture of modified asphalt binder. To simplify the production process and reduce the production cost, amorphous poly alpha olefin (APAO) and polyphosphoric acid (PPA) were applied to prepare highly stable modified asphalt binder. The influence of APAO/PPA on the temperature sensitivity, rheological property, storage stability, compatibility and microstructure of neat binder were studied by rotational viscosity (RV), dynamic shear rheometer (DSR), bending beam rheometer (BBR) and Fourier transform infrared (FTIR) spectroscopy. The results show that the incorporation of APAO/PPA reduced the temperature sensitivity of neat binder. The combined effect of APAO/PPA contributed to the improvement in deformation resistance, which was evidenced by the increase in failure temperature and percent recovery. However, the compound modification of APAO/PPA decreased the binder’s low-temperature performance. APAO strengthened the fatigue resistance of the binder, while PPA reduced the anti-fatigue performance. Composite modified asphalt binder with superior storage stability could be prepared, which was confirmed by the desired Cole–Cole plots and fluorescence imaging. Furthermore, chemical and physical reactions occurred during the APAO/PPA modification process. Overall, 2 wt.% (weight percentage) APAO and 1.5 wt.% PPA are recommended for the production of modified asphalt binder with remarkable rheological performance and storage stability.

Modulating Mechanical and Shape-Memory Properties while Mitigating Degradation-Induced Inflammation of Polylactides by Pendant Aspirin Incorporation.

Synergistically modulating mechanical properties and improving shape-memory performance while mitigating degradation-induced chronic inflammation of polylactide (PLA)-based implants for biomedical applications remain elusive. We test the hypothesis that copolymerizing aspirin-functionalized glycolide with d,l-lactide could enhance the thermal processing, toughness, and shape-memory efficiency of the copolymer while mitigating local inflammatory responses upon its degradation. The content of pendant aspirin was readily modulated by monomer feeds during ring-opening polymerization, and the copolymers with ∼10% or less aspirin pendants exhibited gigapascal-tensile moduli at body temperature and significantly improved fracture toughness and energy dissipation that positively correlated with the aspirin pendant content. The copolymers also exhibited excellent thermal-healing and shape-memory efficacy, achieving a >97% temporary shape fixing ratio at room temperature and facile shape recovery at 50-65 °C. These drastic improvements were attributed to the dynamic hydrophobic aggregations among aspirin pendants that strengthen glassy-state physical entanglement of PLA while readily dissociating under stress/thermal activation. When subcutaneously implanted, the copolymers mitigated degradation-induced inflammation due to concomitant hydrolytic release of aspirin without suppressing early acute inflammatory responses. The incorporation of aspirin pendants in PLA represents a straightforward and innovative strategy to enhance the toughness, shape-memory performance, and in vivo safety of this important class of thermoplastics for biomedical applications.

Characterisation of Colloidal Nanosilica Modified Asphalt binder

Nanosilica (NS) has been used in this study as an asphalt binder modifier to improve the binder properties. Penetration grade 60/70 (PEN 60/70) asphalt binder was modified with NS in colloidal form with an average size of 10 to 15 nanometer (nm). The nanosilica modified asphalt binders (NSMB) were tested for different tests such as physical properties, atomic force microscopy (AFM), dynamic shear rheometer (DSR), multiples stress creep and recovery (MSCR) and asphalt pavement analyser (APA). The result obtained from physical properties shows that the additions of NS significantly improve the properties of base asphalt binder in terms of penetration, softening point and viscosity. It was also found that NSMB is stable during the high temperature storage period. SEM images showed that NS particles dispersed well in base asphalt binder and AFM images showed that the addition of nanosilica in asphalt binder improved its surface stiffness. In addition, NSMB significantly increases the G*/sinδ value, failure temperature, and percentage creep recovery while, decreased the non-recoverable creep compliance, which indicated higher elasticity and beneficial in increasing the rutting resistance as compared to the base asphalt. On the other hand, from APA test, it was found that NSMB reduced the rutting depth of asphalt mixture. It can be concluded from the analysis that a maximum of 2% NS be added into the base asphalt for optimum binder modification.

Effect of Chemical Composition and Structure on the Shape Recovery Temperatures of Titanium Nickelide-Based Alloys

Effect of Chemical Composition and Structure on the Shape Recovery Temperatures of Titanium Nickelide-Based Alloys

All-aerosol-jet-printed highly sensitive and selective polyaniline-based ammonia sensors: a route toward low-cost, low-power gas detection

We report the design and scalable fabrication of a low-cost and low-power polyaniline-based (PANI) ammonia (NH3) gas sensor on polyimide (PI) substrates using additive manufacturing techniques. The silver interdigitated electrode (IDE) arrays and conducting polymer films are printed onto PI using a direct-write technology of aerosol-jet printing. Morphological characteristics are examined by scanning electron microscopy and energy-dispersive X-ray analysis which reveal homogeneously printed PANI film on the IDE platform. The gas sensing performance is evaluated in the analytical early leak detection range of 5–1000 ppm NH3 in air as a function of both thermal (23 °C, 50 °C, 80 °C) and relative humidity (RH = 0%, 30%, 50%) exposures. The sensor exhibits sensitivity down to 5 ppm NH3 with a sub-ppm detection limit and good repeatability. We observe rapid NH3 detection at 0% RH with very extended times for equilibration and recovery. However, at both 30 and 50% RH, the room temperature response and recovery times are reduced to only about 1 min and 5 min, respectively. Experiments also reveal good sensitivity toward the analyte even at higher operating temperatures. Present results merit the practical application of aerosol-jet-printed, low-power sensors for industrial applications where low-level hazardous gas detection is essential.

A comparison of black vs. yellow coat color on rectal and gastrointestinal temperature in Labrador retrievers

Although dark coat color in dogs has been theorized as a risk factor for heat injury, there is little evidence in the scientific literature to support that position. We utilized 16 non-conditioned Labradors (8 black and 8 yellow) in a three-phase test to examine effects of coat color on thermal status of the dog. Rectal, gastrointestinal (GI), and surface temperature using infrared thermography measured at the eye and abdomen, were measured along with respiration rate measured in breaths per minute (bpm), collected at three time points. Phase 1 (Baseline) – 30 minutes of crate rest in a climate-controlled room; Phase 2 (Walking in Sunlight) - 30-minute walk in an outdoor environment on a sunny day; and Phase 3 (Cooling) – 15 minutes of crate rest in climate-controlled room to determine post-exposure recovery temperatures. No effect of coat color was measured for rectal, gastrointestinal, surface temperature, or respiration rate (P > 0.05) in dogs following their 30-minute walk in sunlight. All temperatures measured increased similarly (rectal 1.86°C and 1.80°C; GI 1.92°C and 1.95°C; eye 2.8°C and 1.92°C; abdomen 2.91°C and 2.39°C) in black and yellow dogs respectively, following 30 in Sunlight (P > 0.05). Additionally, temperatures decreased in a similar fashion for both coat colors (rectal 0.84°C and 0.88°C; GI 1.48°C and 1.32°C; eye 1.49°C and 1.70°C; abdominal 1.75°C and 1.5°C) in black and yellow dogs respectively (P > 0.05) during Cooling. Respiration rate increased similarly for both coat colors, (147.2 bpm and 143.7 bpm for black and yellow respectively) when Baseline values were compared to Sunlight values and decreased similarly (28.8 bpm black; 60.2 bpm yellow after Cooling phase (P > 0.05). These novel data reveal a surprising lack of effect for black vs. yellow coat color on body temperature as measured by standard rectal thermometer, gastrointestinal thermistor, or infrared thermography in a population of Labrador retrievers.

Energy/exergy analysis of solar driven mechanical vapor compression desalination system with nano-filtration pretreatment

The performance of the mechanical vapor compression desalination system is limited due to the required vacuum pressure and associated high temperature scaling problem. Thus, a new solar driven mechanical vapor compression desalination plant with nano-filtration pretreatment operating at atmospheric pressure is developed for a production of 500 m3/day. The electrical and thermal energies of the new system are generated using the integration of solar photovoltaic modules and parabolic trough collectors. To evaluate the performance of the new system, energy/exergy analysis is performed by employing a MATLAB package and a Graphical User Interface (GUI) tool. Also, an economic evaluation for the plant's direct, indirect, and unit product costs ($/m3) is presented. The predicted results are validated with the available measurements. The effects of different design parameters such as feed water temperature, distilled and brine water temperature difference, salt rejection and recovery ratio on plant performance are investigated. The proposed plant's exergy efficiency is found to vary from 14.59 to 20% consistently with design parameters. The enhancement in exergy efficiency is estimated to be 153.7%, 56.3%, 32.63% and 27% compared with Multi-Effect evaporation mechanical and conventional vapor compression, forward feed multi-effect mechanical vapor compression and reverse osmosis systems, respectively. The salt rejection and recovery ratio are found to be the most significant parameters to enhance the plant exergy efficiency. Furthermore, the photovoltaic unit has a significant effect on exergy destruction of the plant with a percentage of 85.79%. The parabolic trough collectors also have high exergy destruction of about 69.53%. The economic analysis reveals that the unit water price for the proposed plant is equal to 1.54 $/m3. Therefore, the developed solar-NF-MVC system suits small scale units for remote communities.

Experimental study on moisture migration in soil during coupled heat storage and release processes

The soil around ground heat exchanger is the heat source or heat sink of ground source heat pump system. Most scholars had analyzed the soil heat and moisture migration in heat storage or release process, respectively. In this paper, the coupled heat storage and release experiments were conducted in saturated and unsaturated fine-grained sand under the same excess temperature. The comparison on the soil moisture migration and the temperature and humidity recovery characteristics were analyzed. Results showed that the amount of soil moisture migration is almost symmetrical for the test soil sample during heat storage and release processes under the same excess temperature, the relative difference of moisture migration is within 10%. For a certain initial moisture content, the phenomenon of moisture migration could not occur until the excess temperature reaches a certain value. Similarly, for a certain excess temperature, the phenomenon of moisture migration could not occur until the initial moisture content of soil reaches a certain value. The phenomenon of maximum moisture content exists in heat storage process, but not exists in heat release process. The time required to restore to the initial soil temperature is the same, while the time required to restore to the initial moisture content is different between soil heat storage and release processes. With the increase of the initial moisture content, the humidity recovery time increases.

Fabrication and ethanol sensing of sol–gel grown zinc oxide powder: the effect of cobalt and copper doping

Pure, cobalt and copper doped zinc oxide powder were successfully fabricated by the sol–gel method at different concentrations (i.e., 5 wt% and 10 wt%). Structural and morphological properties of the samples were studied comparatively. Structural analysis of the samples revealed that all of them were polycrystalline zinc oxide in nature; possessing hexagonal wurtzite structure with (101) preferred orientation. The lattice constants were calculated from the most prominent peak and compared with the standard values. Other structural parameters such as strain, crystallite size, dislocation density, stacking fault, and specific surface area were also calculated to have a better investigation. The sensing performance of the samples toward ethanol vapors was investigated for various concentrations of ethanol in air at different operating temperatures in the range of 175–400 °C. The gas sensing performance of the samples was evaluated in terms of gas concentration and operating temperature. Compared to pure zinc oxide, a drastic reduction in the optimal operating temperature and the recovery time was observed after doping. If four different parameters (operating temperature, dynamic response, sensitivity and response and recovery times) were considered simultaneously, the ZCo10 (10% cobalt doped) can be a good option as a sensor material.