Hasil untuk "Heat"

Jesus Paredes, Ruben Echeverria, Borja Prieto et al.

High power density machines are essential in sectors such as aeronautics, automotive and traction. In order to achieve high power densities, cooling systems that are capable of extracting large amounts of heat are required. In this regard, direct cooling systems, in which the stator conductors are in contact with the cooling fluid, are the most promising. For this reason, this paper presents a new direct flooded stator cooling system specifically aimed at conventional plug-in hairpin winding machines. Unlike other cooling systems, the proposed one presents a solution with channels between all its conductors and not only at the top or bottom of the slot. To demonstrate the capabilities of the proposed cooling system, a motorette has been manufactured and experimentally validated. The main characteristics of this cooling system are described, its potential is evaluated by applying it to a 250 kW and 10,000 rpm conceptual aeronautical motor design and, additionally, design guidelines for the sizing of equivalent cooling systems are given.

Qinglin Yang, Yang He, Lukai Zhou et al.

Driven by the combined effects of global warming and the urban heat island (UHI) effect, building energy consumption has been rising steadily in recent years. The photovoltaic-cool roof (PVCR) system has emerged as an effective solution for urban energy conservation and carbon reduction. However, existing research on the energy-saving benefits of PVCR remains relatively limited, and none of these studies have considered the interaction between photovoltaic modules and high-reflectivity roofs (also called cool roof, CR). Therefore, field experiments were conducted to compare the thermal performance of the PVCR system against that of three conventional roof configurations, including photovoltaic roof (PVR), asphalt roof (AR), and CR. The results demonstrate that the PVCR system achieves a remarkable daytime cooling effect, with a maximum temperature reduction of 29 °C compared to the AR system, and maintains lower temperature fluctuations throughout the entire day. In addition, the findings reveal that the photovoltaic modules exhibit a lower average temperature when installed on the cool roof, with a temperature decrease of 0.15 °C relative to the asphalt roof. A numerical model incorporating the photothermal interaction between a high-reflectivity surface and PV modules was developed and validated with experimental data. The numerical model considers the interactions between the photovoltaic (PV) modules and the high reflectivity surface, including shortwave radiation reflection, longwave radiative exchange, and convective heat transfer. The sensitivity analysis indicates that a change in the spacing and height of the PV arrays from 0.3 m to 0.5 m increases the relative energy-saving efficiency of the system. The conclusions drawn in this paper can provide a reference for the application of the PVCR system in hot-summer and cold-winter areas.

Tengyue Pan, Chengming Jiang, Xinmin Shen et al.

In today’s data-driven age, the thermal properties of computer transistors play an important role. In this research, finite element simulation is employed to construct the structural model of the primary components within a computer chassis, and the thermal performance is evaluated based on ambient temperature, thermal conductivity, and heat dissipation rate. By combining the particle swarm optimization algorithm with numerical simulation for joint simulation and structural optimization, the component layout was optimized to reduce the working temperature. The results show that when the background temperature, that is, the ambient temperature, rises from −20 °C to 60 °C, the maximum operating temperature of the computer is approximately 88 °C. The maximum temperature is mainly in the transistor core and the minimum temperature is in the intake grille, and the operating temperature of the optimized structure decreases by approximately 10 °C. The research shows that the operating temperature is most sensitive to the change of background temperature, and the transistor core is the main heating source. The maximum temperature can be reduced by rationally adjusting the position of the components. This study provides a reference for analyzing the thermal performance of computers and optimizing structures.

N. Wildmann, L. Györy

<p>This study demonstrates the feasibility of measuring temperature variance and heat flux with self-calibrated fine-wire platinum resistance thermometers (FWPRT) on multicopter drones. The sensors are especially designed for light weight, fast response-times and to be carried on miniature drones for turbulence measurements. A significant improvement was found in vertical profiling of temperature gradients compared to slower solid-state sensors, demonstrating reduced hysteresis between ascent and descent phases and accurate representation of strong gradients. More than 100 single flights with the sensors attached to drones of the SWUF-3D fleet were carried out in vicinity to a meteorological mast array at the WiValdi wind energy research park in Northern Germany. The comparison to sonic anemometers shows that temperature variance can be accurately measured within the background flow variability. The same applies for heat flux, which was measured for the first time with multicopter UAS and the eddy covariance method without external sensors. Heat flux is a crucial parameter to understand the energy balance of the atmospheric boundary layer and turbulent mixing. An uncertainty below 50 W m<span class="inline-formula">⁻²</span> was determined with the constraint that only low to moderate wind speed conditions (3–8 m s<span class="inline-formula">⁻¹</span>) could be used to allow vertical wind speed measurements with the current algorithm. The results indicate that the temperature sensors are suited for heat flux measurements, but further improvements are necessary with regard to vertical wind speed estimates to decrease the overall uncertainty.</p>

Geng Wei, Zhu Zhibao, Ma Jinhui et al.

Steam oxidation corrosion resistance is an important index to evaluate boiler steel. In this study 9Cr-3Co-2W martensitic heat-resistant steel （/% 0.08C， 0.40Si， 0.40Mn， 9.00Cr， 0.20Ni， 0.50Mo， 1.50 W. 0.05Nb， 0.20V， 0.07N， 0.030Al， 0.0012B， S≤0.010， P≤0.020）， the oxidation kinetics curves of the two groups without rare earth and with rare earth <italic>w</italic>［Ce］ 0.03% in 625 ℃ water vapor environment were carried out， and the morphology and structure of the oxide film were analyzed by SEM and XRD. The results show that the outer layer of iron oxide scale in both sets of experimental steel are mainly rich in Fe oxide Fe₃O₄ or Fe₂O₃， and the inner layer is rich in Cr and Fe oxides （Fe，Cr）₂O₃ and （Fe，Cr）₃O₄ in the 625 ℃ water vapor environment. However， the outer layer of iron oxide scale in the experimental steel without rare earth addition has poor density ， and even cracks appear. The experimental steel with rare earth added has dense outer oxide layer and large chromium-rich oxide layer thickness. On the surface of the oxidation kinetics curve， at the initial stage of oxidation （0 h-200 h）， with the extension of oxidation time， the oxidation rate of the test steel is large. After the oxidation time exceeds 200 h， the oxidation rate gradually decreases， and after 2 000 h， the oxidation rate approaches the level， and the oxidation rate continues to decline and gradually becomes stable. The addition of a small amount of rare earth Ce can help to form a dense oxide film and improve the oxidation resistance of the steel.

Geon-Il Kim, Ji-Hoon Oh, Na-Yeon Shin et al.

Abstract The deep ocean, a vast thermal reservoir, absorbs excess heat under greenhouse warming, which ultimately regulates the Earth’s surface climate. Even if CO2 emissions are successfully reduced, the stored heat will gradually be released, resulting in a particular pattern of ocean warming. Here, we show that deep ocean warming will lead to El Niño-like ocean warming and resultant increased precipitation in the tropical eastern Pacific with southward shift of the intertropical convergence zone. Consequently, the El Niño-Southern Oscillation shifts eastward, intensifying Eastern Pacific El Niño events. In particular, the deep ocean warming could increase convective extreme El Niño events by 40 to 80% relative to the current climate. Our findings suggest that anthropogenic greenhouse warming will have a prolonged impact on El Niño variability through delayed deep ocean warming, even if CO2 stabilization is achieved.

R. G. Vyshnavi, R. K. Samaiya, Anita Babbar et al.

The study was conducted during the rabi seasons (November) of 2021– (April) 2022 and 2022 (November) –2023 (April) in Jabalpur, Madhya Pradesh, India aimed to explore chickpea germplasm responses to high temperature stress under varied sowing conditions. Thirty-two germplasm lines and eight elite varieties were sown under normal and late conditions to coincide with heat stress occurrence (>32°C). The investigation done on phenological data impacted by sowing dates, revealed significant differences between normal and late sowing conditions across critical growth stages. Temporal disparities resulted in an approximate 8-day reduction in days to 50% flowering (DFF), 7 days in days to pod formation (DPF), 9 days in days to seed formation (DSF), and 12 days in days to field maturity (DFM). Conversely, longer-duration genotypes experienced a reduction of around 6 days in DFF, DPF, DSF, and 14 days in DFM. Yield attributes among genotypes varied significantly between different sowing conditions. Under normal (D1) conditions, genotypes exhibited adequate seed yield (kg/ha-1), while late-sown (D2) conditions resulted in considerable percentage decrements of 40.2% reduction in the yield. Post hoc Duncan’s New Multiple Range Test (DNMRT) analysis indicated substantial variability among genotypes for all traits, except for primary and secondary branches, observed across both sowing conditions. The correlation analysis uncovered nuanced associations between phenological stages and yield attributes, emphasizing the complexity of chickpea cultivation dynamics. This study provides valuable insights into optimizing chickpea germplasm for high temperature stress resilience, contributing to the ongoing efforts for sustainable and climate-resilient agriculture.

Arnut Phila, Warin Keaitnukul, Smith Eiamsa-ard et al.

The proper designs of modified heat transfer surfaces or turbulence enhancement inserts for heat transfer augmentation are extremely important for improving overall aerothermal performances relating to the energy-saving capabilities of thermal systems. A major challenge is to control friction loss as little as possible while maintaining reasonable heat transfer enhancement. Transverse baffles with rectangular notches or notched baffles (NBs) were applied for improving aerothermal performance in a channel with a constant aspect ratio of 3.75 while notch height-to-baffle height ratio (a/e) ranged from 0.125 to 0.5. Reynolds number ranged from 6000 to 24,000, in experiments. Heat transfer enhancement, pressure loss, and aerothermal performance in a rectangular channel with notched baffles were examined. Compared to the solid transverse baffle (SB, a/e = 0), the NBs with a/e = 0.125 increased the heat transfer rate while lessening the pressure loss, as shown by the experimental findings. Obviously, Nusselt number, friction factor and aerothermal performance increased as the a/e ratio decreased. The NBs with the smallest notch height-to-baffle height ratio (a/e = 0.125) exhibited the highest aerothermal performance of 1.17, which can be attributed to the efficient heat transfer enhancement by the strong multi-jet impingements and the moderate friction loss penalty resulting from the presence of notches (spaces) on the baffles.

Ahmad Zulkefly, Wan Norlina Wan Azman, Julia Omar et al.

This case-control study, conducted at the Hospital USM BestARi unit, aimed to identify the serum metabolic fingerprint among individuals with breast lumps and healthy controls, and to discover potential biomarkers. Serum samples from healthy controls, benign breast lump patients, and malignant breast lump patients were analyzed using proton nuclear magnetic resonance spectroscopy (1H NMR). A multivariate data analysis approach was employed, with the OPLS-DA and clustered heat map techniques effectively differentiating between the three groups. The study revealed significant metabolite variations across the groups and proposed D-glucose, glycerol, and glycine as potential biomarkers for breast cancer diagnosis. Metabolic pathways such as alanine, aspartate, glutamate metabolism, and glycine, serine, and threonine metabolism were implicated. The metabolomics approach coupled with multivariate analysis successfully identified key metabolites leading to group separation and suggested altered metabolic pathways. However, further research and integration with other ‘omics’ technologies are necessary for clinical translation.

Yun-Hui Kim, Bo-Yeon Kim, Jin-Myung Kim et al.

Honeybee vitellogenin (Vg) transports pathogen fragments from the gut to the hypopharyngeal glands and is also used by nurse bees to synthesize royal jelly (RJ), which serves as a vehicle for transferring pathogen fragments to the queen and young larvae. The proteomic profile of RJ from bacterial-challenged and control colonies was compared using mass spectrometry; however, the expression changes of major royal jelly proteins (MRJPs) in hypopharyngeal glands of the honeybee <i>Apis mellifera</i> in response to bacterial ingestion is not well-characterized. In this study, we investigated the expression patterns of <i>Vg</i> in the fat body and <i>MRJPs 1–7</i> in the hypopharyngeal glands of nurse bees after feeding them live or heat-killed <i>Paenibacillus larvae</i>. The expression levels of <i>MRJPs</i> and <i>defensin-1</i> in the hypopharyngeal glands were upregulated along with <i>Vg</i> in the fat body of nurse bees fed with live or heat-killed <i>P. larvae</i> over 12 h or 24 h. We observed that the expression patterns of <i>MRJPs</i> and <i>defensin-1</i> in the hypopharyngeal glands and <i>Vg</i> in the fat body of nurse bees upon bacterial ingestion were differentially expressed depending on the bacterial status and the time since bacterial ingestion. In addition, the <i>AMP</i> genes had increased expression in young larvae fed heat-killed <i>P. larvae</i>. Thus, our findings indicate that bacterial ingestion upregulates the transcriptional expression of <i>MRJPs</i> in the hypopharyngeal glands as well as <i>Vg</i> in the fat body of <i>A. mellifera</i> nurse bees.

Welligton Conceição da Silva, Éder Bruno Rebelo da Silva, Maria Roseane Pereira dos Santos et al.

This study aimed to evaluate the behavior and thermal comfort of 20 Girolando cows (5/8-H/G), with light and dark coats, in the wettest period of the year, in Santarém, Pará, Brazil, in pasture with access to shade, and plenty of drinking water and mineral salt. Animal behavior categories were computed for 12 h a day, on 3 days in a row, by trained observers. Three day shifts were considered: Morning (6:00 a.m. to 9:55 a.m.), Intermediate (10:00 a.m. to 01:55 p.m.) and Afternoon (2:00 p.m. to 05:55 p.m.). The Temperature Index (TI), the Black Globe Humidity Index (BGHI) and the Comfort Index (CI) were calculated to measure thermal comfort. At all times studied, BGHI pointed that the environment was outside the thermal comfort zone. Dark-coated animals spent more 34.26% of the time in activities in the shade. The light-coated animals remained more 11.88% of the time in the sun, performing their natural behaviors. Both light and dark coat animals remained more 77 and 74.44% of the time in the sun, respectively. The behavior “in the sun while grazing” was the most evident, in both coats, in the studied shifts. The behaviors “in the shade while walking” and “in the shade while standing idle” were more evident (p &lt; 0.01) in dark-coated cattle. The grazing behavior was higher in animals with dark coat (p &lt; 0.05). In all evaluated shifts, there was a positive correlation between the behavior “in the sun while grazing” with the CI (r = 0.44211; p &lt; 0.0305). Behaviors performed in the shade, such as “idleness while lying down,” “ruminating while lying down and standing up,” and behaviors “in the sun,” “idleness while lying down” and “ruminating while lying down,” were negatively correlated with CI. It is concluded that, even in the wettest period of the year, in the Eastern Amazon, Girolando dairy cows are exposed to hot environments, which causes thermal discomfort and changes in their natural behavior, as they spend more time standing in shaded areas, usually in rumination. Also, light-coated cows spend more time in the sun, while dark-coated cows spend more time in the shade. Thus, light-coated cows tend to have health and zootechnical performance negatively affected.

Yuhang Zhu, Aihua Zhang, Chang Liu et al.

Background: Early puerperal rehabilitation can interfere with a woman’s ability to care for herself and her infant. Acupoint hot compress, with a combination of acupoints and natural physical agent heat, has significant potential to alleviate symptoms experienced during early puerperium. Current evidence regarding the effects of acupoint hot compress therapy on early puerperal rehabilitation is insufficient. The aim of this study is to address this with a multi-center design and large sample size. Methods: This is a prospective, multi-center, and randomized controlled clinical trial. A total of 1400 nulliparous women with a singleton pregnancy experiencing natural childbirth from 14 hospitals will be enrolled and randomly allocated to either an intervention group or a control group in a 1:1 ratio. Subjects in the control group will only receive routine postpartum care. In addition to routine postpartum care, the subjects in the intervention group will be administered a 4-hour acupoint hot compress with a constant temperature of 45 ± 2 ∘C respectively within 30 minutes after delivery, 24 hours and 48 hours after delivery. The primary outcome will be the time elapsed from delivery to the first urination. The secondary outcomes will be postpartum uterine contraction pain intensity, the Edinburgh Postnatal Depression Scale for screening postpartum depression and the assessment of lactation including recording the lactation initiation time, postpartum diet, appetite, weight, neonatal weight. Discussion: These results will provide evidence for obstetricians and parturients on considering nonpharmacologic and noninvasive intervention in early puerperal rehabilitation.

Kihyuck Choi, Jinhee Choi, Pyeong An Lee et al.

Plant-associated microbiota plays an important role in plant disease resistance. Bacterial wilt resistance of tomato is a function of the quantitative trait of tomato plants; however, the mechanism underlying quantitative resistance is unexplored. In this study, we hypothesized that rhizosphere microbiota affects the resistance of tomato plants against soil-borne bacterial wilt caused by Ralstonia solanacearum. This hypothesis was tested using a tomato cultivar grown in a defined soil with various microbiota transplants. The bacterial wilt-resistant Hawaii 7996 tomato cultivar exhibited marked suppression and induction of disease severity after treatment with upland soil-derived and forest soil-derived microbiotas, respectively, whereas the transplants did not affect the disease severity in the susceptible tomato cultivar Moneymaker. The differential resistance of Hawaii 7996 to bacterial wilt was abolished by diluted or heat-killed microbiota transplantation. Microbial community analysis revealed the transplant-specific distinct community structure in the tomato rhizosphere and the significant enrichment of specific microbial operational taxonomic units (OTUs) in the rhizosphere of the upland soil microbiota-treated Hawaii 7996. These results suggest that the specific transplanted microbiota alters the bacterial wilt resistance in the resistant cultivar potentially through a priority effect.

Zhenhua Zheng

21-4N is a typical heat resistant steel used as the material of exhaust valves. The application of cross wedge rolling to manufacture preform for valves has the advantages of higher efficiency and better quality. In this study, cross wedge rolling of 21-4N with an area reduction ratio of 65% was experimentally studied. Twelve groups of different tool parameters of cross wedge rolling tests were carried out. It is found that a larger stretching angle or a smaller forming angle is better for surface quality. When the stretching angle is 7&deg; and the forming angle is less than 25&deg;, a smooth surface can be obtained. Furthermore, the influence of stretching angle on central quality is not obvious, but a greater forming angle is prone to get a better central quality. When the forming angle is larger than 30&deg;, no central damage was found in the workpieces. Considering the balance of surface quality and central quality, a stretching angle of 7&deg; and a forming angle of 30&deg; is a suitable combination for cross wedge rolling of 21-4N with an area reduction ratio of 65%.

Seyed Ehsan Hosseini, Evan Owens, John Krohn et al.

In small-scale combustors, the ratio of area to the combustor volume increases and hence heat loss from the combustor&#8217;s wall is significantly enhanced and flame quenching occurs. To solve this problem, non-premixed vortex flow is employed to stabilize flames in a meso-scale combustion chamber to generate small-scale power or thrust for propulsion systems. In this experimental investigation, the effects of thermal recuperation on the characteristics of asymmetric non-premixed vortex combustion are studied. The exhaust gases temperature, emissions and the combustor wall temperature are measured to evaluate thermal and emitter efficiencies. The results illustrate that in both combustors (with/without thermal recuperator), by increasing the combustion air mass flowrate, the wall temperature increases while the wall temperature of combustor with thermal recuperator is higher. The emitter efficiency calculated based on the combustor wall temperature is significantly increased by using thermal recuperator. Thermal efficiency of the combustion system increases up to 10% when thermal recuperator is employed especially in moderate Reynolds numbers (combustion air flow rate is 120 mg/s).

Jason M Bourke, Wm Ruger Porter, Lawrence M Witmer

Convoluted nasal passages are an enigmatic hallmark of Ankylosauria. Previous research suggested that these convoluted nasal passages functioned as heat exchangers analogous to the respiratory turbinates of mammals and birds. We tested this hypothesis by performing a computational fluid dynamic analysis on the nasal passages of two ankylosaurs: Panoplosaurus mirus and Euoplocephalus tutus. Our models predicted that Panoplosaurus and Euoplocephalus would have required 833 and 1568 thermal calories, respectively, to warm a single breath of air by 20°C. Heat recovery during exhalation resulted in energy savings of 65% for Panoplosaurus and 84% for Euoplocephalus. Our results fell well within the range of values for heat and water savings observed in extant terrestrial amniotes. We further tested alternate airway reconstructions that removed nasal passage convolutions or reduced nasal vestibule length. Our results revealed that the extensive elaboration observed in the nasal vestibules of ankylosaurs was a viable alternative to respiratory turbinates with regards to air conditioning. Of the two dinosaurs tested, Euoplocephalus repeatedly exhibited a more efficient nasal passage than Panoplosaurus. We suggest that the higher heat loads associated with the larger body mass of Euoplocephalus necessitated these more efficient nasal passages. Our findings further indicate that the evolution of complicated airways in dinosaurs may have been driven by the thermal requirements of maintaining cerebral thermal homeostasis.

B. Rastogi, M. Berkelhammer, S. Wharton et al.

<p>Carbonyl sulfide (OCS) has recently emerged as a tracer for terrestrial carbon uptake. While physiological studies relating OCS fluxes to leaf stomatal dynamics have been established at leaf and branch scales and incorporated into global carbon cycle models, the quantity of data from ecosystem-scale field studies remains limited. In this study, we employ established theoretical relationships to infer ecosystem-scale plant OCS uptake from mixing ratio measurements. OCS fluxes showed a pronounced diurnal cycle, with maximum uptake at midday. OCS uptake was found to scale with independent measurements of <span class="inline-formula">CO₂</span> fluxes over a 60&thinsp;m tall old-growth forest in the Pacific Northwest of the US (45<span class="inline-formula">^∘</span>49<span class="inline-formula">^′</span>13.76<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M4" display="inline" overflow="scroll" dspmath="mathml"><msup><mi/><mrow><mo>′</mo><mo>′</mo></mrow></msup></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="6pt" class="svg-formula" dspmath="mathimg" md5hash="72877009115e133fe632a10b0040889b"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-15-7127-2018-ie00001.svg" width="8pt" height="6pt" src="bg-15-7127-2018-ie00001.png"/></svg:svg></span></span>&thinsp;N, 121<span class="inline-formula">^∘</span>57<span class="inline-formula">^′</span>06.88<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M7" display="inline" overflow="scroll" dspmath="mathml"><msup><mi/><mrow><mo>′</mo><mo>′</mo></mrow></msup></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="6pt" class="svg-formula" dspmath="mathimg" md5hash="9162d003e0ed94af8b7d2b4a38708019"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-15-7127-2018-ie00002.svg" width="8pt" height="6pt" src="bg-15-7127-2018-ie00002.png"/></svg:svg></span></span>&thinsp;W) at daily and monthly timescales under mid–high light conditions across the growing season in 2015. OCS fluxes were strongly influenced by the fraction of downwelling diffuse light. Finally, we examine the effect of sequential heat waves on fluxes of OCS, <span class="inline-formula">CO₂</span>, and <span class="inline-formula">H₂O</span>. Our results bolster previous evidence that ecosystem OCS uptake is strongly related to stomatal dynamics, and measuring this gas improves constraints on estimating photosynthetic rates at the ecosystem scale.</p>

Sobar Ihsan

Jenis penukar kalor sangatlah beragam dan masing masing dirancang untuk memenuhi kebutuhan yang spesifik. Namun demikian jenis shell & tube sejauh ini merupakan jenis yang paling banyak dipergunakan berkat konstruksinya relatif sederhana dan memiliki keandalan karena dapat dioperasikan dengan beberapa jenis fluida kerja. Efek pendinginan yang dihasilkan dalam sistem refrigerasi tergantung dari efektivitas kinerja kondensor. Sementara, kinerja kondensor semakin lama akan menurun seiring dengan terjadinya fouling factor. Pada penelitian ini dilakukan analisis optimasi sistem termal pada kondensor shell and tube sebagai Alat Penukar Kalor (APK). Dari hasil optimasi kondensor shell and tube dengan menggunakan analisis full factorial yang di validasi dengan sofware Heat Transfer Research Inc (HTRI) dan disimulasi Computational Fluid Dynamics (CFD). Didapat hasil optimum adalah diameter shell 720 mm, jumlah tube 192 buah, diameter tube 38.1 mm, panjang tube 3 m, beda temperatur rata-rata LMTD 8.86 K, dan dengan koefesien perpindahan panas menyeluruh U 1448.21 W/m2K. Dalam penentuan parameter temperatur desain kondensor sistem cooling-tower, harus mempertimbangkan kinerja cooling-tower dan perubahan temperatur udara. Kata kunci: kondensor, optimal, shell and tube

Wang Wenyi, Mao Xiaoqian, Hu Bin et al.

Theoretical analysis of a heat pump with an economizer have been presented in this paper. The mathematic models of the heat pump system have been developed and experiments have been conducted to investigate the impacts of the gas injection on heat pump performance under low ambient temperatures. The results indicate that the heating capacity and the power consumption go up when the amount of gas injection increases under low ambient temperatures. The discharge temperature declines with the increment of gas injection, while the COP of the heat pump rises first and then descends. According to the test results, the optimal amount of gas injection is about 10%-14% of the total mass flow rate in the heat pump system.

Julio Buchmann

In earlier papers of a series of real data integrations of the National Center for Atmospheric Research Community ClimateModel with tropical heat anomalies display regions of pronounced subsidence and drying located several thousand kilometers westwardpoleward of the heating for cases of tropical Atlantic heating and tropical east Pacifi c heating. This highly predictable sinking responseis established within the fi rst fi ve days of these integrations. The normal-modes of a set of adiabatic primitive equations linearizedabout a basic state at rest are used to partition model response into gravity-inertia and Rossby modes. The most important contributionfor the vertical motion response comes from the gravity modes added for all vertical modes. The principal emphasis is given upon thecontributions of the second and third internal vertical modes (with equivalent depths on the order of a fews hundred meters) for thevertical motion response.