Cooling Air Temperature Research Articles

Assessment of a Cowl-Incorporated Wind-Powered Forced-Air Evaporative Cooler for Preservation of Fruit and Vegetables

This paper reports the performance of a cowl-incorporated wind-powered forced-air evaporative cooler for preservation of fruit and vegetables. The evaluation took place in the Department of Mechanical Engineering, Obafemi Awolowo University, Ile-Ife in October. Freshly harvested tomatoes were used in the evaluation as tomatoes were common locally and are highly perishable. The produce (2.5 kg) was kept in the cooling chamber of the evaporative cooler, and the changes in weight were observed three times daily until the produce had lost more than 7 % of its weight. The no-load cool air temperatures ranged between 27.3and 34.5oC corresponding to ambient dry bulb temperatures 29.0and 43.9oC respectively. The no-load cool air relative humidity ranged between 63.0 and 87.2% corresponding to ambient relative humidity of 40.8 and 79.5% respectively. The evaporative cooler no-load cooling efficiency was 66.7% while the cooling efficiency when loaded was 50.0%. The evaporative cooler was able to preserve tomatoes for 9 days losing 4.8 % weight. The evaporative cooler had the potential of effectively preserving fruit and vegetables without dependence on electricity. If used in windier and less humid regions, the average cooling efficiency of the evaporativecooler would be higher than that observed in this research.

Simulating the impact of ventilation corridors for cooling air temperature in local climate zone scheme

Climate change and urbanization are impacting urban microclimates, necessitating careful consideration in urban ventilation planning. However, there remains uncertainty regarding the identification and examination of urban ventilation corridors (VCs), and their mechanisms for urban heat mitigation. This study combined ENVI-met and the least-cost path (LCP) algorithm to simulate the VCs within the local climate zone (LCZ) scheme, with Guangzhou as an example. The results show that (1) VCs constructed using the LCP method are primarily distributed along vegetation and rivers, bypassing high-temperature aggregation in high-density/high-rise building areas; (2) The cooling effect of VCs varies across different LCZs, influenced by factors such as land use, vegetation, building, and topography. (3) In low-density, low-rise LCZs, VCs significantly reduce temperatures by about 0.23°C, while in high-density, high-rise LCZs, the cooling effect is weaker, with a reduction of only around 0.01°C. This study highlights the importance of preserving hydrological system and optimizing green space layout to enhance urban ventilation thus mitigate heat accumulation.

Analytical design and computational fluid dynamics analysis for optimizing fixed ventilation systems for power transformer: Numerical study and experimental validation

Despite the recognized fact that power transformers (PT) are highly efficient technology, part of their electrical energy is counted as heat losses. Therefore, the cooling system is a critical factor in the life span and performance of the PTs, and hence the adopted thermal energy design can be strongly effective. This study revolves around the innovative development of a novel generation of fixed ventilation fans for PTs, achieved through Computational Fluid Dynamics (CFD) simulations and practical experiments. The proposed CFD model was developed adopting ANSYS FLUENT 19.2. The proposed CFD model was verified by comparing the numerical and experimental results of the cooling air temperature and velocity. A standard k-ε model was used to simulate the airflow of the investigated cooling system numerically. A thermal analysis of a four-sided power transformer was performed, and an analysis of the optimum position to install the cooling fan on the radiator was presented. The most effective number of used fans was also determined. The main results showed that two fans were found to be the best performance among the tested candidate alternatives. The two cooling fans’ size, material, and cover shape were also studied and added to the proposed model. Besides, the utilization of a thermoelectric generator was considered in this study in order to recycle some of the lost heat into output power. An experimental prototype mimicking the actual cooling system for the power transformer was designed and fabricated. Results showed that the selected material has achieved a high Calculated Factor of Safety (FoS) equal to 237, indicating that the utilization of the designed parts is of high safety.

Micro and macro urban heat islands in an industrial city: Bradford, UK

The urban heat island (UHI) phenomenon refers to the temperature difference(s) between urban/built environments and suburban/natural areas. It affects energy use, health, water quality, and in brief, the quality of life in cities. Understanding the magnitude of this issue could help urban planners and decision makers to better implement green interventions into their cities. This paper shows the results of field measurements carried out to study the UHIs in Bradford, as one of the most deprived cities in the UK with minimum green infrastructure. In the first phase of the study, air temperatures were measured in twenty locations (four areas) with different land covers in Bradford. These measurements were called micro UHI study, as the air temperatures were measured in areas within the boundaries of the city. Data were collected in late summer and early winter. The results showed that the UHI is more sensible in the colder day (with average 0.6 °C cooler air temperature in a green area compared to the city centre). Greener areas experienced higher wind and lower air temperatures compared to dense urban settings in December. In the second phase of the study (macro scale), diurnal air temperatures from a residential (urban) versus a rural site were compared during a heat wave episode (seven days). It was observed that the rural site was 0.8 °C cooler than the residential/urban site. The maximum temperature differences occurred during the nights/early mornings between the two sites (3.2 °C at 5:00am).

Assessing the effect of coastal upwelling on the air temperature at the south-eastern coast of the Baltic Sea

Coastal upwelling along the SE Baltic Sea coast is a common feature, especially during the warm season. It significantly lowers sea surface temperature (SST) in the coastal areas, and, therefore, may be responsible for modifying meteorological conditions in those coastal areas, where upwelling is most frequently observed. This study aims to assess the effect of coastal upwelling on the air temperature at the south-eastern coast of the Baltic Sea based on long-term period observations (2002–2021) from coastal hydrometeorological stations and satellite data. Overall, our study revealed that due to its high frequency and spatial extent, upwelling is responsible for lowering the mean summer season SST of the SE Baltic Sea coast by about 1°C. And even though upwelling is a short-term event, upwelling-induced SST drop results in cooling air temperatures in the coastal areas, i.e., the mean air temperatures during upwelling are typically 2−4°C lower than before. It was also observed that upwelling is favouring the development of advective fog. Thus, sudden changes in meteorological parameters during upwelling can have versatile effects on various socio-economic activities. The results of this study contribute to the understanding of upwelling feedback onto the lower atmosphere and, therefore, are important for advancing the accuracy of weather forecasts that are needed for coastal communities, including marine and coastal industries.

Earlier ice melt increases hypolimnetic oxygen despite regional warming in small Arctic lakes

AbstractAlthough trends toward earlier ice‐out have been documented globally, the links between ice‐out timing and lake thermal and biogeochemical structure vary spatially. In high‐latitude lakes where ice‐out occurs close to peak intensity of solar radiation, these links remain unclear. Using a long‐term dataset from 13 lakes in West Greenland, we investigated how changing ice‐out and weather conditions affect lake thermal structure and oxygen concentrations. In early ice‐out years, lakes reach higher temperatures across the water column and have deeper epilimnia. Summer hypolimnia are the warmest (~ 11°C) in years when cooler air temperatures follow early ice‐out, allowing full lake turnover. Due to the higher potential for substantive spring mixing in early ice‐out years, a warmer hypolimnion is associated with higher dissolved oxygen concentrations. By affecting variability in spring mixing, the consequences of shifts in ice phenology for lakes at high latitudes differ from expectations based on temperate regions.

Preparation and application of profiled luminescent polyester fiber with reversible photochromism materials

Abstract In this study, we realized a highly luminescent polyester fiber using a special spinneret orifice comprised of eight C-shaped pores and specific process parameters. A moderate amount of reversible photochromism materials was added along with the specific color masterbatch of suitable materials. With its high light transmittance and reflectance, the fabric has high glossiness and excellent transparency and exhibits dazzling color effects with changes in ambient light intensity. The raw materials used are polyethylene terephthalate (PET) chips with a low melting point of 110–150°C, 0.3–0.5% (active ingredient 30%) masterbatch, and 40–50% (active ingredient 50%) reversible photochromism masterbatch. The following process parameters were also chosen: for the PET chips, the drying temperature was 80–90°C, the drying time was 12–14 h, the masterbatch drying temperature was 70–80°C, the drying time was 8–10 h, the spinning temperature was 220–230°C, the cooling air temperature was 15–17°C, the cooling air speed was 0.45–0.50 m·min−1, the first hot roller temperature was 75–80°C, and the secondary hot roller had the heater turned off.

Geese migrating over the Pacific Ocean select altitudes coinciding with offshore wind turbine blades

Abstract Renewable energy facilities are a key part of mitigating climate change, but can pose threats to wild birds and bats, most often through collisions with infrastructure. Understanding collision risk and the factors affecting it can help minimize impacts on wild populations. For wind turbines, flight altitude is a major factor influencing collision risk, and altitude‐selection analyses can evaluate when and why animals fly at certain altitudes under certain conditions. We used GPS tags to track Pacific Flyway geese (Pacific greater white‐fronted goose, tule greater white‐fronted goose and lesser snow goose) on transoceanic migrations between Alaska and the Pacific Coast of the contiguous United States, an area where offshore windfarm development is beginning. We evaluated how geographic and environmental covariates affected (1) whether birds were at rest on the water versus in flight (binomial model) and (2) altitude selection when in flight (similar to a step‐selection framework). We then used a Monte Carlo simulation to predict the probability of flying at each altitude under various conditions, considering both the fly/rest decision and altitude selection. In both spring and fall, geese showed strong selection for altitudes within the expected rotor‐swept zone (20–200 m asl), with 56% of locations expected to be within the rotor‐swept zone under mean daylight conditions and 28% at night. This indicates a high possibility that migrating geese may be at risk of collision when passing through windfarms. Although there was some variation across subspecies, geese were most likely to be within the rotor‐swept zone with little wind or light tailwinds, low clouds, little to no precipitation and moderate to cool air temperatures. Geese were unlikely to be in the rotor‐swept zone at night, when most individuals were at rest on the water. Synthesis and applications. These results could be used to inform windfarm management, including decisions to shut down turbines when collision risk is high. The altitude‐selection framework we demonstrate could facilitate further study of other bird species to develop a holistic view of how windfarms in this area could affect the migratory bird community as a whole.

A Study of a Two-Phase Heat Transfer Mechanism in a Vertical Sintering Cooling Furnace

In order to explore the law of gas–solid countercurrent cooling heat transfer in a vertical sinter cooling furnace at a high temperature, based on the Euler model and the local non-thermodynamic equilibrium theory, an exergy efficiency model was built to evaluate the heat transfer process in the vertical sinter cooling furnace with different parameter changes. It was found that the inlet temperature of cooling air and sinter inlet temperature are the main factors affecting the temperature field and gas–solid heat transfer characteristics in the furnace. Under the conditions of each parameter, the cooling air temperature presents a radial “M” shape distribution. The axial cooling section is the most intense area of gas–solid heat transfer, and this part has the best heat transfer effect. When the inlet temperature of cooling air and the inlet temperature of sinter increase, the outlet temperature of sinter and the outlet temperature of cooling air increase. When the sinter equivalent diameter increases, the cooling air outlet temperature decreases gradually, while the sinter outlet temperature increases gradually. When the diameter and height of the cooling section increase, respectively, the outlet temperature of the sinter decreases and the outlet temperature of the cooling air increases. Based on dimensional analysis, the heat transfer correlation formula suitable for certain test conditions is obtained.

Application of a Ranque–Hilsch Vortex Flow in an Internal Cooling of a Gas Turbine Engine Blade

Abstract The efficiency of a gas turbine engine is directly impacted by the turbine inlet temperature and the corresponding pressure ratio. A major strategy, aside from the use of costly high-temperature blade materials, is increasing the turbine inlet temperature by internally cooling the blades using pressurized air from the engine compressor. Understanding the fluid mechanics and heat transfer of internal blade cooling is, therefore, of paramount importance for increasing the temperature threshold, hence increasing engine efficiency. This article presents modeling and test results of a novel cooling approach, one in which the Ranque–Hilsch vortex flow is adopted for the first-row gas turbine blade cooling. Simulation and test results demonstrate the successful formation of continuous Ranque–Hilsch vortex flow by injecting compressed air into a cylindrical chamber equipped with seven air inlets. At an inlet pressure of 100 kPa, the outlet temperature from the vortex tube dropped 255 °C, which allowed the blade temperature to cool by 47 °C. When a total inlet pressure of 300 kPa was admitted, the drop-in temperature reached 65 °C. The device has the potential to drop the cooling air temperature below the freezing point with increased inlet pressure. The thermal efficiency of the gas turbine blade increased by about 3% when vortex cooling with 10% mass of partially compressed air was extracted at about 910 kPa. For the tested scenario of a 17 MW power output, the partial extraction had a better efficiency increment than extraction at full compression, which was 1200 kPa.

Structural Integrity of Turbine Stator Blades Using Different Super Alloys with Internal Cooling at Fluid Temperature Range of 600 K – 700 K

The importance of turbines in power generation cannot be overstated. While the failure in stationary plants can lead to downtime and high repair costs, its failure in mobile plants like the jet engines can be catastrophic with attendant loss of lives. Hence, by all possible means, the prevention of turbine failure is a necessity, and a very good means of doing this is with the use of super-alloys. Super-alloys are tailored to withstand the demands of turbine operations especially stress and elevated temperature and pressure. The blades are thus, manufactured from super-alloys, and of prominence are the Nickel-based super-alloys. The performance of five different super-alloys: (DS) GTD 111, Ti-6Al-4V, Inconel 718, CMSX-4, and Nimonic 80A was simulated using COMSOL MultiPhysics 5.5 at cooling air temperature range of 600 K – 700 K. The mode of cooling employed in the study is only internal cooling. With the developed stress percentage of the yield stress value and the stator blade displacement at the operating conditions as the criteria of performance, super-alloy Ti-6Al-4V faired as the best material for the stator blade.

Indigenous literacy of local knowledge about the signs of natural disaster A case of Way Ela Natural Dam - Maluku

Introduction. Various natural disasters occurred in Maluku, with one of the impacts is changing the land surface. One example is a forest has changed into a hill or a river has changed into a natural dam. In Maluku, Way Ela natural dam was formed as a resultof the disaster in 2012 and was destroyed again by the disaster in 2013. This natural event that occurred in a relatively short period of time is still remembered by the community. This study aims to explore the types of local knowledge about dam disasters based on their memories. 
 Data Collection Method. Data collection in this study was conducted by the interviews.
 Data Analysis. Data were analyzed by grouping the themes on natural signs of the formation and of the broken of the dam. 
 Results and Discussion. The formation of dams begins with earthquakes, landslides, dry rivers, and strange animal behavior. Natural signs before a broken-down dam are earthquakes, heavy rain, cracked ground, strange behavior of animals, and changes in cooler air temperature.
 Conclusion. This study concludes that the community is aware of three types of disaster signs including the formation of a dam, before the dam breaks, and when the dam breaks.

How does humidity data impact land surface modeling of hydrothermal regimes at a permafrost site in Utqiaġvik, Alaska?

Humidity is a basic and crucial meteorological indicator commonly measured in several forms, including specific humidity, relative humidity, and absolute humidity. These different forms can be inter-derived based on the saturation vapor pressure (SVP). In past decades, dozens of formulae have been developed to calculate the SVP with respect to, and in equilibrium with, liquid water and solid ice surfaces, but many prior studies use a single function for all temperature ranges, without considering the distinction between over the liquid water and ice surfaces. These different approaches can result in humidity estimates that may impact our understanding of surface-subsurface thermal-hydrological dynamics in cold regions. In this study, we compared the relative humidity (RH) downloaded and calculated from four data sources in Alaska based on five commonly used SVP formulas. These RHs, along with other meteorological indicators, were then used to drive physics-rich land surface models at a permafrost-affected site. We found that higher values of RH (up to 40 %) were obtained if the SVP was calculated with the over-ice formulation when air temperatures were below freezing, which could lead to a 30 % maximum difference in snow depths. The choice of whether to separately calculate the SVP over an ice surface in winter also produced a significant range (up to 0.2 m) in simulated annual maximum thaw depths. The sensitivity of seasonal thaw depth to the formulation of SVP increases with the rainfall rate and the height of above-ground ponded water, while it diminishes with warmer air temperatures. These results show that RH variations based on the calculation of SVP with or without over-ice calculation meaningfully impact physically-based predictions of snow depth, sublimation, soil temperature, and active layer thickness. Under particular conditions, when severe flooding (inundation) and cool air temperatures are present, care should be taken to evaluate how humidity data is estimated for land surface and earth system modeling.

Impact of topography and land cover on air temperature space-time variability in an urban environment with contrasted topography (Dijon, France, 2014–2021)

The influence of topography and land cover on air temperature space-time variability is examined in an urban environment with contrasted topography through simple and multiple linear regression (SLR and MLR) models, ran for each hour of the period 2014–2021, to explain spatial patterns of air temperature measured by a dense network. The SLR models reveal a complementary influence of topography and land cover, with the largest influence during daytime and nighttime, respectively. The MLR significantly improves upon the SLR models despite persistent intensity errors at night and spatial errors in the early morning. Topography influences air temperatures all year round, with temperature decreasing with height during the day and frequent thermal inversions at night (up to 30% of the time). Impervious surfaces are more influential in summer and early fall, especially during the late afternoon for the fraction covered by buildings and during the early night for the distance from the city centre. They contribute to increase air temperature close to the city centre and where the fraction covered by buildings is large. By contrast, vegetation contributes to cool air temperature during the night, especially in spring and early summer for field crops, summer and early fall for forests, and late fall and winter for low vegetation. Our framework proves to be a low-cost and efficient way to assess how strongly and how recurrently the static surface conditions influence air temperature along the annual and diurnal cycles. It is easily transposable to other areas and study fields.

Investigation of the cooling and purification effect of automobile exhaust using heat pipe heat exchanger

Heat pipe heat exchangers (HPHEs) have excellent heat transfer performance and have been applied in many fields. However, the cooling and purification effects of the HPHE on the automobile exhaust are still not clearly acknowledged. In this paper, an HPHE applied to automobile exhaust cooling and purification was designed and developed. By establishing 3D physical model and mathematical model, the influences of heat pipe inclination angles and cooling air temperatures on the cooling effect of the automobile exhaust are studied. And the cooling and purification effects under different engine speeds have been studied experimentally by connecting the HPHE to a 1.8 T Volkswagen Passat car. The results indicate that when the dip angle is 30°, the heat exchanger has the best cooling effect. When the engine speed reaches 3000 rpm, the heat removed by the cooling air reaches a peak of 3.06 kW with the maximum cooling efficiency of 56.37 %. The HPHE has a certain purification effect on the SO2 and NOx in the automobile exhaust. The maximum purification rates are 15.4 % and 13.8 %, and the peak purification rates appear at 2000 rpm and 2500 rpm, respectively, while the purification effect on the CO is not obvious.

Dynamic modelling and performance prediction of a novel direct-expansion ice thermal storage system based multichannel flat tube evaporator plus micro heat pipe arrays storage module

Direct-expansion ice thermal storage (DX-ITS) system can improve the energy efficiency ratio (EER) by integrating the evaporator and the storage module. In this paper, a dynamic model for a DX-ITS system is developed to predict system behavior. This system consists of multichannel flat tube evaporator plus micro heat pipe arrays storage module, a 4-HP compressor using R134a, an air-cooled condenser with 40 m2 area and an electronic expansion valve. On this basis, the influences of the condenser's cooled-air temperature, cooled-air flow rate, and compressor speed on the system energy and thermodynamics performance are studied. Results show that the EER and the charging power could reach 2.24 and 5.41 kW, respectively, under cooled-air temperature, cooled-air flow rate, and compressor speed of 28.5 °C, 4660 m3/h, and 1450 rpm. The exergy efficiency is more sensitive to cooled-air temperature, which decreases by 22.48% from 11.52% to 8.93% as the cooled-air temperature increases from 18 °C to 35.5 °C. Moreover, the compressor has the highest exergy destruction ratio of 40%–55% in the exergy analysis of the system component, while the condenser has the lowest exergy destruction ratio of 7%–15%, indicating that optimizing the compressor is the key to improving the system's performance.

Inventaritation and Potential Utilization of Macroscopic Mushroom in TPKh Tenjo KPH Bogor

The TPKh Tenjo KPH Bogor is a production forest wood collection area and becomes a production forest for the Acacia mangium wood species. Timber harvesting activities leave a lot of tree stumps, twigs, or piles of wood that do not pass production. Environmental conditions with a lot of harvested wood residue and supported by relatively cool air temperatures and high humidity, it is suspected this area has a diversity of macroscopic fungi with various unknown potentials. This study aims to obtain data on the types of macroscopic fungi and their potential uses. The research method includes the stages of exploration, identification and literature study to obtain the potential of the macroscopic fungi found. The research succeeded in finding 8 types of macroscopic fungi classified into the phylum Basidiomycota, 3 orders, 5 families, and 7 genera. The macroscopic fungi include Coprinellus sp., Lentinus sp., Panus sp., Schizophyllum commune, Pycnoporus sp., Fomitopsis sp. 1, Fomitopsis sp. 2, and Lycoperdon sp. Based on the results of the literature study, the potential uses of macroscopic fungi were found are as food, medicine, natural pigment producer, and enzyme producer. This data report can be used as basic information on the use of macroscopic mushrooms by communities around the area to be used as food or medicinal ingredients. Further utilization of this data is the development of the potential of macroscopic fungi that produce enzymes, pigments or drugs to be produced on a large scale. Research on the development of potential mushroom conservation strategies can also be carried out for sustainable use.

Behavioral and physiological responses to an inspired-air supplemental cooling system for dairy cows in free-stall housing.

During heat stress, dairy cows spend less time lying down to dissipate heat. Heat stress abatement strategies generally target cows outside of their resting areas. However, cooling cows while in their stalls could help alleviate heat stress without compromising lying behavior. The objective of this study was to assess the effects of an inspired-air supplemental cooling system (SCS) on respiration rate, rectal temperatures, lying behavior, rumination time, and milk production (energy-corrected milk, ECM) of lactating dairy cows. A free-stall pen was retrofitted with custom stall partitions to deliver cooled air and mist. The pen, including the stall platform, was divided into two separate sides. Twenty-eight lactating Holstein cows were randomly sorted into two groups, each housed on one side of the experimental pen. Cows experienced four treatments (control, CTRL; cooled air, AIR; mist, MIST; cooled air and mist, AIR+MIST) in a four-treatment, four-period, two-sequence crossover design, with each period lasting seven days. Cooled air was provided continuously, and mist was cycled 3min on, 12min off from 0900 to 2100h. Respiration rates were observed hourly between 0900 and 1500h, and only measurements recorded while cows were lying down were used in the analysis. Rectal temperatures of 16 focal cows were recorded at 1545h once per day. Lying behavior and rumination were recorded continuously, and milk yields recorded twice daily were used to calculate ECM. Throughout the experimental period, the average temperature-humidity index was 66.4±6.07. During the MIST treatment, the respiration rate was lower than the CTRL (45.7 vs 49.0±1.92 breaths/min) and AIR (45.7 vs 48.7±1.92 breaths/min). CTRL and AIR did not differ (48.7 vs 49.0±1.92 breaths/min), and MIST and AIR+MIST (45.7 vs 47.1±1.92 breaths/min) did not differ. All other variables were not significantly different between treatments. In conclusion, the SCS appeared to be tolerated by cows and shows the potential to assist in alleviating heat stress. The cooling capacity needs to be evaluated under more extreme environmental conditions causing heat stress than those experienced during this study. Further testing is required to determine the cooled air temperature specifications and mist delivery frequency.

Investigation of the ENVI-met model sensitivity to different wind direction forcing data in a heterogeneous urban environment

Abstract. As the frequency of extreme heat events in cities is significantly increasing due to climate change, the implementation of adaptation measures is important for urban planning. Microclimate modelling approaches enable scenario analyses and evaluations of adaptation potentials. An ENVI-met microclimate model was setup for a heterogeneous urban study area in Cologne/Germany characterized by closed building structures in the eastern part and an urban park area in the western part. The goal of this paper is to evaluate the model sensitivity and performance to different wind direction forcing and demonstrate the importance of accurate wind forcing data for precise microclimate modelling evaluated with sensor measurements. To this end, we compared simulated air temperatures at 3 m height level using measured wind direction forcing data with simulated air temperatures using constant wind direction forcing from west, north, east and south direction. All other forcing data like wind speed were kept exactly the same as in the reference run. This sensitivity study was performed for a warm summer day in 2022. The model results of all five model runs (reference plus four scenarios) were compared to microclimatological measurements derived from one station of a dense meteorological sensor network located in the study area using the simulated mean air temperatures. We found significant temperature differences between the four sensitivity tests and the reference run as well as to the sensor measurements. Temperature differences between the reference run and the measurements were small and a high statistical model fit could be determined (Nash Sutcliffe Model Efficiency Coefficient/NSE = 0.91). The four model runs with constant wind directions showed significantly larger differences to measurement data and a worse statistical correlation between simulated and observed data (NSE between 0.62 and 0.15). For constant west winds, cooler air temperatures and higher wind speeds were found in the urban park and in the streets and courtyards east of the park. Constant east wind causes warmer air temperatures in the urban park area and lower wind speeds in the street canyons and inner courtyards. This shows that cooling effects in adjacent building blocks due to the greened urban park largely depend on the wind direction. The sensitivity tests show that the wind direction effect can result in local air temperature differences of up to 4 K on average. These results shows that even on summer days with low wind speeds, accurate wind direction data is highly relevant for accurate air temperature simulation. This finding can have important implications for urban planning and the design of green infrastructures in cities, e. g. for the design of fresh air corridors.

Study of the temperature conditions of power transformers elements for example transformers at substation «Kabun-І» (Syrian Arab Republic)

RELEVANCE. Any device loses its performance over time, Power transformers too. The problems of overheating and insulation are the main influencing factors to the operation status of power transformers. Thus, the study is of high relevance and applied demand, because the heating ofpower transformer elements, especially in the territory of the Syrian Arab Republic, can reach 46 °C. Monitoring the state ofpower transformers is of decisive importance in the study of reliability and safety indicators in the power system. Thermal stress is one of the main parameters to be controlled. Sharp fluctuations in the temperature of the transformer winding, oil, insulating medium, etc. affect the operating conditions, sen’ice life and safety of transformers. PURPUSE. Determination of the type of functional dependences of the heating temperature of windings and oil ofpower transformers on their loading. METHODS. Determination of the type of functional dependences of the change in the temperature of the windings and oil of power transformers using the methods of statistical data processing, approximating functions and assessing their reliability. RESULTS. Approximating functions of the main temperature parameters ofpower transformer elements have been developed - a function of the temperature of the average overheating of the winding above the oil temperature; function of the temperature of the average overheating of the oil above the temperature of the cooling air; oil superheat temperature function above the cooling air temperature; superheat function of the hottest spot above the cooling air temperature. The coefficients of determination of the obtained temperature functions of the average overheating of the winding and the average approximation error are determined. As a result of the research, it was found that the polynomial function is the most reliable. The developed dependencies can be used for practical application to assess and analyze the heating temperature of oil and transformer windings with a known load, as well as to control the operating modes of electrical equipment and consumers of electrical energy in power supply systems.