Building integrated photovoltaic (BIPV) glazing is currently regarded as a promising building material with a wide range of benefits. Photovoltaic combined vacuum glazing is a relatively new ...innovative concept in BIPV glazing. On the other hand, photovoltaic combined hybrid vacuum glazing (PVCHVG) is a rarely studied topic in which an air gap exists between vacuum glazing and photovoltaic glazing to form an insulated glazing unit. This paper investigates the overall energy-saving performance of a CdTe-based semi-transparent PVCHVG. A dynamic simulation model was developed and validated with an outdoor experiment to explore the energy-saving performance of the PVCHVG under five different climate conditions in China, and the results were compared with commonly used window systems. The results indicated good insulation properties against both heat loss and heat gain due to the combined action of vacuum glazing and semi-transparent photovoltaic glazing. Compared to clear single-glazing and double-glazing window systems, PVCHVG can save overall energy consumption up to 59.39% and 39.97% in heating-dominated region, and 76.33% and 73.766% in cooling-dominated region, respectively. Furthermore, the PVCHVG window system generated electricity with a good performance ratio and total system efficiency ranging from 85.7% to 85.78% and 7.45%–7.55%, respectively, considering five climate conditions.
•A CdTe-based STPV glazing combined hybrid vacuum glazing is investigated.•A dynamic simulation model is developed and validated with an outdoor experiment.•It poses inferior heat loss and heat gain in 5 distinct climate conditions in China.•The energy-saving potential is better in cooling than heating-dominated regions.•Key performance parameters for the window PV system are discussed.
In this review, there is an overarching emphasis on the extrapolation of knowledge from one physiological regulator to another, with a particular emphasis on autonomic thermoregulation in humans and ...rodents. Through mammalian phylogenetics, one finds evidence for the gradual acquisition of an ability to maintain whole-body thermal stability, with discrete autonomic mechanisms arising for the generation, retention and dissipation of thermal energy. The sequential attainment of those thermoeffectors, over aeons, makes it unlikely that they are controlled by a common central processor, so the presence of a single activation switch is perhaps inconceivable. Instead, effector activation is associated with the arrival at lower and upper critical (threshold) body temperatures, with regions between those points defining zones of mammalian thermoneutrality. As thermal energy content deviates from thermoneutrality, there is a progression from purely passive (physical) heat exchanges through to autonomic (thermoeffector) recruitment. That activation is morphologically dependent, with an obligatory greater basal metabolic heat production evident in smaller individuals within both hypo- and normothermic states. Indeed, a first-principles, morphological case is presented for the existence of an effector recruitment cascade, with human observations providing the empirical support. That sequential activation is consistent with the presence of multiple central controllers, and both animal and human experiments supporting that possibility are reviewed. Finally, the case is presented that mammals possess multiple thermoreceptive fields, thermoeffectors with discrete neural pathways and several central, but independent, controllers of thermoeffector function. Those concepts are summarised in updated conceptual and neuronal models for human thermoregulation.
•Evidence concerning the independent control of mammalian thermoeffectors was interrogated.•Phylogenetic evidence, hypothalamic ablation and human experiments were evaluated.•It is postulated that mammals have multiple receptive fields, thermoeffectors and central controllers.
Due to the operating temperature from 900 K to 1300 K produced by the concentrating ratio over 2000 in solar parabolic dish-engine system, the natural convection heat loss driven by the buoyancy ...force of air contributes an important role in the energy loss of cavity receiver. 3-D numerical simulations were performed and the results are analyzed from the novel viewpoint of field synergy principle (FSP) in order to study the heat transfer and fluid flow characteristics in natural convection heat loss of cavity receiver. The effects of geometric parameters, including the inclination angle, aperture size, aperture position and cavity geometric shape on the natural convection heat loss of cavity receiver were examined. The FSP analysis on the simulation results demonstrates that FSP can well explain the reduction mechanism for natural convection heat loss of cavity receiver because the smaller inner production of velocity vector and temperature gradient always corresponds to the lower Nusselt number occurred in the cases with lager inclination angle, smaller aperture size, lower aperture position and frustum-cylinder cavity, respectively. Therefore, the reducing natural convection heat loss attributes to the weakening synergy between velocity vector and temperature gradient. In addition, the local heat transfer performance is studied by the presented distributions of heat transferred via fluid motion, where more interesting natural convection heat loss characteristics of cavity receiver and the detailed explanations were provided. The results of this work offer benefits for the development of theory and technique about reducing natural convection heat loss of cavity receiver.
•Natural convection heat loss characteristics of a solar cavity receiver were studied.•The reduction mechanism of natural convection heat loss was explained.•The local heat transfer performance of natural convection heat loss was studied.•Some interesting natural convection heat loss characteristics were found.
•A hybrid approach was developed to improve heavy oil recovery.•Hydrophilic nanofluids were combined with steam injection technologies.•Core flooding experiment resulted in a nanoparticle ...concentration of 0.05 wt%•The method produced increased oil recovery using Berea Sandstone.•Steam consumption and adverse environmental impact was reduced.
The need to minimize in situ heat loss and reduce steam consumption are the main challenges in using steam injection as an enhanced oil recovery (EOR) method for heavy oil. Nanofluids, with their unique thermophysical characteristics, have been successfully used in redesigned thermal systems for various engineering applications, including EOR operations. In this study, a nanofluid-assisted steam injection approach for the enhanced recovery of heavy oil is investigated where a hot hydrophilic nanofluid (HNF) slug is injected, followed by superheated steam (SHS) in a second slug, to effectively synergize the recovery mechanisms of both EOR agents. Initial core flooding experiments were conducted using ZrO2, TiO2, Fe2O3 and ZnO HNFs for the selection of nanoparticle type, concentration, and injection rate. Hot Formation Water (HFW), instead of HNFs, was used as a reference fluid. Superheated steam flooding was tested, and it significantly outperformed continuous HNF injection which slightly improved IFT and wettability. The proposed nanofluid-assisted steam injection approach was tested using ZrO2 and ZnO for three different HNF/SHS PV ratios. Pressure and temperature profiles were continuously monitored to investigate thermal performance and potential formation damage, however this was not observed. The proposed approach significantly improved oil recovery to a maximum of 68%, using 0.50 PV HNF-ZrO2/0.5 PV SHS, compared with 52.9% if 1.0 PV of SHS had been used. No change in oil composition or water content was observed, suggesting that the observed increase in recovery is due to the thermophysical properties of the hydrophilic nanoparticles which improve the thermal performance of the SHS injection and increase oil mobility. Thus, this study presents a promising first-of-a-kind approach which can substantially reduce steam consumption by up to 50% while also improving oil recovery through the utilization of nanotechnology.
Long-term assessments of bio-thermal responses in a hair coat sheep breed were performed to investigate the effect of the thermal environment on their physiological performance and thermal balance. ...Twelve healthy non-lactating Morada Nova ewes (3 ± 1.2 years old, body mass 32.7 ± 3.7 kg) were assigned in two 12 × 12 latin square designs (from 07:00 to 19:00 h and from 19:00 to 07:00 h, respectively) for assessments of their bio-thermal responses during 24 consecutive days. There was a monophasic pattern in the ambient temperature (TA), which ranged between 21 and 38 °C, thereby exposing the ewes to different levels of surrounding TA over the day and influencing several of their bio-thermal responses (P = 0.0001). Their body temperatures (i.e., rectal, skin, and hair coat surface temperatures) gradually increased (P = 0.0001) from 04:00 h. The mean peak for rectal temperature (39.3 °C) was recorded at 19:00 h, while for skin and hair coat surface temperatures it occurred at 13:00 and 14:00 h, respectively. The sensible heat loss by long wave radiation and surface convection exceeded the metabolism of ewes when the TA was below 24 °C, which usually occurred between 24:00 and 06:00 h. During exposure to higher ambient temperatures, the sheep increased respiratory evaporative heat loss, without panting. In conclusion, the sheep regulated rectal temperature within a relatively narrow range of 1.4 °C over 24 h, and appear to be well adapted to coping with heat. Minimum 24 h body temperature was correlated with minimum TA, indicating that heat conservation strategies are likely to be important for Morada Nova sheep in a tropical biotype at night, when rates of sensible heat loss exceed the heat generated by metabolism.
•The ambient temperature ranged between 21 and 38 °C, thereby exposing ewes to different levels of surrounding air temperature.•The sheep increased respiratory evaporative heat loss, without panting.•The sensible heat loss exceeded the metabolism of ewes when the TA was below to 24 °C.•The Morada Nova sheep could have some difficulties in conserving their body heat nocturnally.
A novel ladle shroud was employed to produce small bubbles to remove inclusions smaller than 50 μm meanwhile inhibiting the formation of slag eye. Both water modeling and industrial tests were ...carried out to confirm the generation of small bubbles with the ladle shroud. The numerical model was developed to investigate slag-metal interfacial behaviors, considering the effects of bubble sizes and distributions. The gas flux through the surface was employed to evaluate the impact of bubble swarm on slag layer. The results show that reducing bubble sizes can effectively disperse bubbles passing through the slag layer, so as to inhibit the formation of slag eye, under the same gas flow rate. The diameter of slag eye matches well 1.7 times diameter of the region with gas flux higher than 0.0025 m/s. The heat loss of the entire tundish was estimated, considering the convection and radiation heat transfer of slag eye.
Characteristic diameters of the slag eye, regions with bubble escape and gas flux, under different bubble conditions. Display omitted
•The impact of bubbles on slag layer was characterized by surface gas flux.•Micro-bubbles were observed by online sampling the liquid steel in bubbly region.•The heat loss of liquid steel was predicted, considering the impact of slag eye.
Nowadays, with the advancement of construction technology, saving energy use of the building has been considered as one of the fields of environmental sustainability. The use of green cover and ...plants on the buildings is a suitable passive method that leads to the replace reduced urban green spaces and reduce the problems caused by the effect of the urban heat island (UHI) and improve the energy performance of buildings by reducing the indoor temperature, regulating humidity and creating thermal insulation. The objective of this study was to evaluate the reduction of energy consumption through the green walls of an educational building in Gorgan (Csa climate). For this purpose, first, a building designed on the university site, and the effects of two methods of constructing green walls by using three different plant species were simulated. For comparison, thermal data of a building with a direct green facade in the same climate was measured as an experimental sample, and the results were used in the simulation. The effects of using two methods of a green wall with three different plant species (Sedum, Parthenocissus tricuspidata, Hedera helix) were simulated, which Sedum has had better results than other species. The final results showed that the latent heat of the building is increased by green walls and less significant heat is generated in the environment than buildings without green cover. Also, in buildings with living green walls, compared to buildings with direct green facades, the thermal transmittance of the wall is reduced due to more material layers. The results show that some types of green walls reduce heat loss, and finally the total energy use of the building. The green wall has a more efficient effect on the buildings with a simple form and the limited number of interior spaces. In general, depending on the variables of each building, the use of green walls with plant species is different. It is better for a building before design, to determine the most appropriate method of constructing a green wall and plant species to reduce the energy usage according to project factors and climate type of the region.
Subantarctic Mode Water (SAMW) in the Pacific forms in two distinct pools in the south central and southeast Pacific, which subduct into the ocean interior and impact global storage of heat and ...carbon. Wintertime thickness of the central and eastern SAMW pools vary predominantly out of phase with each other, by up to ±150 m between years, resulting in an interannual thickness see‐saw. The thickness in the eastern (central) pool is found to be strongly positively (negatively) correlated with both the Southern Annular Mode (SAM) and El Niño–Southern Oscillation (ENSO). The relative phases of the SAM and ENSO set the SAMW thickness, with in phase reinforcing modes in 2005–2008 and 2012–2017 driving strong differences between the pools. Between 2008 and 2012 out of phase atmospheric modes result in less coherent SAMW patterns. SAMW thickness is dominated by local formation driven by SAM and ENSO modulated wind stress and turbulent heat fluxes.
Plain Language Summary
The Southern Ocean around Antarctica is a dominant pathway for moving heat and carbon from the atmosphere into the ocean interior, trapping it for hundreds of years. Most of this uptake is achieved through the formation of “mode waters”, homogeneous layers of water several hundred meters thick, by sinking and overturning as surface waters cool in winter. We find that two distinct pools of mode water in the South Pacific vary dramatically in winter thickness and volume from year to year. They vary in opposition to one another; when one is thicker than normal the other is thinner, with the pattern reversing after a year or so. We show that this “see‐saw” in thickness is strongest when the two main atmospheric patterns of climate variability over the Southern Ocean are reinforcing one another and weaken when they oppose one another. The combination of these patterns of atmospheric variability sets local mode water thickness via surface winds and ocean heat loss. The discovery of such strong dependence of mode water heat content on these atmospheric patterns is important for climate. Atmospheric variability is predicted to change into the future, potentially impacting heat uptake by mode waters and influencing global surface temperatures.
Key Points
South Pacific Subantarctic Mode Water (SAMW) layers display large (±150 m) changes in thickness from year to year
Two distinct pools of South Pacific SAMW exist and their thicknesses see‐saw out of phase with one another
The phase and magnitude of variability are set by changes in wind stress and heat flux driven by the main atmospheric modes of variability
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