Highest Ambient Temperature Research Articles

Single hole ammonia spray macroscopic and microscopic characteristics at flare and transition flash boiling regions

As a potential zero-carbon fuel for internal combustion engine to mitigate the greenhouse gas emission, ammonia’s unique flash boiling spray behaviors have not been well understood. In this study, the macroscopic and the microscopic characteristics of the liquid ammonia spray at the flare and transition flash boiling regions were experimentally investigated under different pressure ratios (RP, the ambient over the saturated pressure) and ambient temperatures. The spray macroscopic morphologies captured from the high-speed camera in the flare flash boiling region (RP ≤ 0.47) show that the spray expands significantly in radial direction while that in the transition flash boiling region (0.47 < RP ≤ 1.06) is more contracted in the penetration direction. Additionally, in flare flash boiling region, spray tip penetration and velocity increases generally with the increase of RP, while that in the transition flash boiling region in versus. Furthermore, the microscopic droplet statistics clearly demonstrate show that the most probable droplet diameter moves to a larger value with the increase of RP. The peak probability of droplet size and the droplet number density decreases at larger RP cases, resulting in a more uniformly distributed droplet sizes and an increased Sauter Mean Diameter. Finally, the ambient temperature show limited influence on the macroscopic spray penetration behaviors or the microscopic droplet size distribution, but evaporation is significantly enhanced since at highest ambient temperature, there are minimized droplet number density in some of the test locations.

28 Effects of low-dose electrolyte supplementation to university horses in light to moderate exercise

Electrolyte supplementation is a frequent practice in human and equine athletes, as exercise in hot and humid weather can exacerbate electrolyte and fluid losses. Previous equine electrolyte research has focused on supplementation of horses in heavy or very heavy workloads with limited research in horses in light to moderate workloads. The objective of this research was to determine if a low-dose electrolyte supplement would benefit university horses in light to moderate exercise during hot and humid weather, with the intention to elucidate information regarding electrolyte supplementation to other lesson programs or horse owners. The study covered 5 consecutive weekdays during mid-September in Murfreesboro, Tennessee, with record high temperatures (33 to 37°C) and humid weather. Eleven mature stock-type horses from the Middle Tennessee State University teaching and research herd were selected for the study, with 5 horses assigned to the treatment group and 6 horses assigned to the control group. Treatment horses received a low-dose oral electrolyte supplement daily for 5 d comprised of 0.07g NaCl/kg of body weight (BW) and 0.02g KCl/kg BW, and control horses received 0.09g/kg BW granulated sugar as a placebo. All horses received their normal diet of Purina Strategy concentrate and prairie grass hay. Measurementsincluded 24-h water intake, fasted blood glucose, and plasma concentrations of sodium, potassium, and chloride. Throughout the week studied, each horse was ridden daily. Riders for each horse were blinded to treatments and completed a Qualtrics survey following each ride to assess their perceptions of horse performance and willingness to work. Data were analyzed using a mixed model with repeated measures or a GLM procedure when appropriate (SAS 9.4) with significance set at P < 0.05. Rider-perceived horse fatigue (P = 0.23) and willingness (P = 0.47) were not different between treatments. Day had an effect on water consumption (P < 0.01), with average water consumption peaking at 37L on d 3 with the highest ambient temperature (37°C), while treatment did not affect water consumption (P = 0.94). Treatment did not affect horse weight (P = 0.66), or serum levels of sodium (P = 0.18), potassium (P = 0.92), and chloride (P = 0.26). Average blood glucose tended to be higher in control animals (P = 0.06), however they were receiving granulated sugar as a placebo. These results suggest that horses in light to moderate work receiving a commercial concentrate may not require additional low-dose electrolyte supplementation.

A Road Map to Detect the Foremost 3E Potential Areas for Installation of PV Façade Technology Using Multi-Criteria Decision Making

A procedure to prioritize the cities to utilize a building integrated photovoltaic thermal (BIPV/T) system is proposed in which the technique for order of preference by similarity to ideal solution (TOPSIS) is employed as a systematic decision-making method. Electricity generation and heat recovery in a year from the energy side, levelized cost of electricity (LCOE), and payback period (PBP) from the economic viewpoint, as well as the carbon dioxide savings from the environmental perspective, are taken into account as the decision criteria. They are the key economic, environmental, and energy (3E) performance indicators of the system. The novelty of the proposed research approach is two items. The first item is systematic and could be employed for each and every case. Moreover, another item is that selection is made based on energy, economic, and environmental (3E) criteria all together, as the important aspects of an energy system. Having introduced the procedure, it is utilized to rank five cities in Iran for the installation of BIPV/T technologies. The cities are Tehran, Tabriz, Yazd, Rasht, and Bandar Abbas, where each one is a populated city from one of the climatic conditions of the country. According to the results, a high priority is seen for two cities: the first city is Yazd with the highest ambient temperature and relative humidity among the alternatives, and the other city is Tehran, with the highest natural gas and electricity tariffs, as well as the greatest price for operating and maintenance. The values of heat recovery, electricity generation, carbon dioxide savings, PBP, and LCOE for Yazd are 42.3 MWh, 23.4 MWh, 16.8 tons, 5.48 years, and 9.45 cents per kWh. The corresponding values for Tehran are 35.6 MWh, 21.6 MWh, 15.0 tons, 2.79 years, and 8.71 cents per kWh, respectively.

The Effect of Urban Form on the Heat Island Phenomenon and Human Thermal Comfort: A Comparative Study of UAE Residential Sites

The Urban Heat Island (UHI) has a detrimental impact on human thermal comfort and the health of city dwellers through raising average temperatures. Urban geometry is one of the factors that affect the intensity of the UHI phenomena. The purpose of this research is to evaluate and compare traditional vs. modern urban forms with respect to temperature and thermal comfort in the United Arab Emirates. Three of each were chosen based on their densities and form. Traditional buildings in the UAE differ from others in the Middle East in that they are primarily single-story, while in the surrounding countries of the region, such as Iran, Iraq, and Saudi Arabia, they are mainly two stories. The UAE climate also has its distinct characteristics. Each configuration was investigated using the ENVI-met urban microclimate simulation software. The comparisons were made for three seasons: summer, winter, and spring. Each configuration was evaluated through four parameters: building shape, street geometry, orientation, and urban density. The results revealed that the low-density traditional urban form exhibited the lowest air temperature in August because it has a low sky view factor (SVF), high height-to-width ratio, and less density. The highest ambient temperature was observed in the sites with low-medium density, lowest height/width ratio, and maximum SVF. The high-density modern urban form displayed lower air temperatures in the summer season than the low and low-medium-density modern urban sites due to the building form, high height-to-width ratio, low SVF, and wind corridors. The traditional compact urban form in Al Fahidi, which has the highest urban density of the six configurations, achieved the best thermal comfort levels in the summer due to the sizable height-to-width ratio and lowest SVF.

Study of the characteristics of germanium avalanche photodiodes in the photon counting mode

A study was made of the characteristics of photodetectors for fiber-optic communication lines using quantum cryptographic systems – germanium avalanche photodiodes operating in the photon counting mode. In particular, it was established at what highest temperature the implementation of the photon counting mode is possible, and the influence of temperature and overvoltage on the sensitivity of photodiodes is also considered. An experimental setup has been developed for the research. It has been determined that the highest ambient temperature at which LFD-2 germanium avalanche photodiodes operate in the photon counting mode is 243 K. It has also been found that the highest sensitivity of germanium avalanche photodiodes corresponds to the optical radiation wavelength range of 1310÷1490 nm. Lowering the temperature leads to an increase in the sensitivity of germanium avalanche photodiodes. It was found that the dependence of the signal-to-noise ratio on overvoltage has a maximum corresponding to overvoltage ΔU = 0.1 V. Lowering the temperature led to an increase in sensitivity and signal-to-noise ratio. Since there was no shift in the maximum dependence of the signal-to-noise ratio on the overvoltage, it was therefore concluded that when the avalanche photodiode operates in the photon counting mode, in order to ensure maximum sensitivity, it is necessary to select the overvoltage corresponding to the maximum signal-to-noise ratio. The results obtained can be used in quantum cryptographic systems, technical means of protecting information transmitted over fiber-optic communication lines, and for the metrology of single-photon radiation sources.

Interrelationship between diseases and calving season and their impact on reproductive parameters and milk production of tropical dairy cows.

The interactions between calving season, the occurrence of retained placenta, intrauterine infections (IUI), and early mastitis, and their effects on the reproductive performance and milk yield of Holstein-Friesian cows in a tropical environment were studied using data from 3320 calvings (1948 cows) from two farms in El Salvador. Based on environmental conditions, season of calving was categorized into: quadrimester 1 (November-February), quadrimester 2 (March-June), and quadrimester 3 (July-October) where quadrimester 2 and 3 had the highest ambient temperature and relative humidity, respectively. Cows were classified into 1, 2, and 3 + parities. The effects of quadrimester and of diseases on days to first service, services per conception, days open, interval between services and 305-day milk yield were studied in separated multivariate regressions. The likelihood of experiencing a disease contingent on the calving season and the likelihood of a cow being culled due to poor fertility associated with experiencing a disease were evaluated using logistic regression. Cows calving in quadrimester 2 and 3 were more likely to suffer from IUI and showed poorer reproduction than cows calving in quadrimester 1. Reproduction was more strongly affected by IUI. Mastitis increased the days to first service, days open, and interval between services. Mastitis and IUI also caused a lower 305-day milk yield. Overall, hotter and more humid conditions lead to higher incidence of disease and poorer reproductive performance. The physiological responses that lead to these phenomena should be further studied to understand the interactions between diseases, environmental conditions and reproduction.

Analysis on Fire-Retardant Performance of non-Class 1E Cables Depending on the Ambient Temperature Condition Surrounding the Facilities for Flame Test of Cables

Electrical cables are extensively used in nuclear power plants. Therefore, the fire-retardant performance of electrical cables is generally verified according to the Institute of Electrical and Electronics Engineers (IEEE) 383 standard, which describes the requirements for flame testing of cables. However, the IEEE 383 standard only stipulates one requirement for the minimum ambient temperature (5°C) surrounding the facilities for the flame test. To analyze the influence of the ambient temperature on the fire-retardant performance of 5cables, flame test experiments were conducted on two types of non-Class 1E cables under several conditions with respect to the seasonal ambient temperatures surrounding the experimental facilities. According to the results, the burning lengths of the cables did not increase in proportion to the increase in the ambient temperature. The longest burning lengths of the cables were obtained from experiments conducted in the autumn season, and not the summer season (with the highest ambient temperature). To investigate these experimental trends, we analyzed the influence of the ambient temperature on the flammability of the cables in terms of the consumption rate of the propane fuel used for the flame tests and the evaporation rate of volatile cable materials. Consequently, it was found that the highest flammability of the cables was observed under autumn conditions, similar to the standard temperature conditions in accordance with the IEEE 1202 standard and in which the volatile materials in the cables did not evaporate more than in the summer condition.

Novel Gel-Polymer Electrolytes for Sodium-Ion Secondary Batteries - An Electrochemical Impedance Spectroscopic Studies

Global lithium deposits have been consumed a lot because of the heavy usage of lithium-ion batteries (LIBs) in almost all portable electronic devices and in automobiles. Due to the very limited global lithium resources, the so-called ‘batteries beyond lithium-ion’ such as sodium-ion batteries (SIBs) are becoming popular, particularly in the R&amp;D level. One of the common problems in the commercial level production of SIBs is the synthesis of suitable electrolytes with sufficient ambient temperature ionic conductivities. In this work, a set of novel gel-polymer electrolytes (GPEs) based on poly (methyl methacrylate) (PMMA) host polymer have been synthesized and characterized by electrochemical impedance spectroscopic (EIS), DC polarization and cyclic voltammetric (CV) techniques. The optimized PMMA-NaClO4-EC-DMC GPE composition (10:14:38:38 wt.%) showed an ambient temperature ionic conductivity of 8.4 mS cm-1. Ionic conductivity vs inverse temperature showed Arrhenius behavior with almost same activation energies of 0.16 eV for all the compositions studied. DC polarization test on SS/GPE/SS configuration showed that the best conducting composition is dominantly an ionic conductor (tion ~ 0.998) with negligible electronic conductivity, which is highly desirable to avoid short circuits within the cell. The CV test on best conducting composition revealed that the electrochemical stability window (ESW) of these GPEs is about 4 volts (- 2 to + 2 volts). This optimized composition with highest ambient temperature ionic conductivity and negligible electronic conductivity seems to be a promising candidate for practical applications in sodium-ion secondary batteries.

Energy saving and production increase of mixed refrigerant natural gas liquefaction plants by taking advantage of natural cold sources in winter

Generally speaking, natural cold sources, such as seawater or air, are often used in natural gas liquefaction processes to cool the compressed refrigerant and natural gas. Since both the required refrigeration and the performance of compressors are closely related to ambient temperature, natural gas plants are designed according to summer operating conditions, because the highest ambient temperature in summer results in the highest refrigeration requirement of the system. However, in winter conditions, with the decline of ambient temperature, precooling by natural cold source can reach lower temperature. When the cooling capacity of natural cold sources is fully utilized, the already built natural gas liquefaction plant can not only reduce energy consumption, but also increase production in winter. To realize cleaner production, this paper comparatively investigated the potential of three mixed refrigerant liquefaction processes, which includes the single mixed refrigerant (SMR), dual mixed refrigerant (DMR) and propane precooled mixed refrigerant (C3MR) processes, for energy reduction and production increase in winter. Based on the optimal conditions under different ambient temperature obtained by genetic algorithm, the specific power consumption, heat transfer performance, as well as changes of typical process parameters such as the flow rate and composition of mixed refrigerants are studied to analyze the effect of natural cold source on the process. When the ambient precooling temperature drops from 40 °C to 10 °C, the specific power consumption of the three processes declines by 20.84%–24.97%, and when it drops to −10 °C, the specific power consumption of the three processes can be reduced by 34.31%–40.53%, which means huge benefit of power-saving. While keeping the volume flow of the compressor in winter the same as that in summer, the SMR process and C3MR process have the largest (26.6%–54.6%) and smallest (16.1%–25.4%) production increase potentials, respectively. Further study is conducted to analyze the load changes of key equipment and economic benefits after changing into energy saving mode or production increase mode in winter. The results indicate that both mode in winter is feasible for the processes with the help of natural cold source, and this may bring considerable increase in economic profits.

Management of flying insects on expressways through an academic-industrial collaboration: evaluation of the effect of light wavelengths and meteorological factors on insect attraction

Insect outbreaks often occur in the absence of natural enemies and in the presence of excess suitable host materials. Outbreaks of gypsy moths are especially problematic in remote areas located in high-latitude regions in Japan because the majority of adults emerge during the short summer season and initiate synchronous mass flight toward artificial lights. The aggregation of moths in public facilities not only is an annoyance to visitors but also permits the establishment of new populations the following year. The aim of this study was to establish a method to reduce the numbers of large moths that are attracted to lights in the rest areas of expressways in Hokkaido based on the results of research on their behavioral ecology and physiology. First, we conducted extensive insect surveys using light traps that emit light at different wavelengths; the traps were set along the expressways in the summers of 2014–2018. The insects attracted to the light were roughly classified into those showing a preference for broadband light wavelengths (from UV-A to green) and short light wavelengths (from UV-A to blue). The former included aquatic insects and winged ants, and the latter included moths and beetles. Next, we analyzed correlations between moth emergence and daily meteorological data. When gypsy moths were abundant during an outbreak, the daily catch of gypsy moths was positively correlated with the highest ambient temperature on the catch day but not with the visibility range, wind speed, or moon phase. In contrast, the daily catch of oak silkmoths did not correlate with any of these parameters. Our results provide guidance for the management of forest insects inhabiting cool-temperate to subarctic regions based on light wavelengths with reference to weather variables.

Rudimentary analysis for solar chimney enhancement

This paper presents fundamental results for solar chimney enhancement. Solar radiation proves to be an important factor in influencing the efficiency of the solar chimney power plant, but its effects on the ambient conditions outside the system has not been considered. Using the Discrete Ordinates radiation model on the semi-transparent collector component of the two-dimensional system, the work presented in this paper simulates the velocity and temperature inside the solar chimney as the ambient temperature of air outside is varied from 307 K to 314 K. At the highest ambient temperature, results show an increase in air velocity of 0.55 m/s at ground level and 1.85 m/s at a height of 1 m along the chimney. To further investigate of this study, a simulation model to include the ambient domain is proposed as a conclusion.

Seasonal growth dynamics and maximum potential growth rates of Australasian snapper (Chrysophrys auratus) and yellow-eyed mullet (Aldrichetta forsteri)

Seasonality can have a major influence on growth dynamics of temperate teleosts that alternates between sustaining the maximum growth performance and confining it to its minimum. Yet the effects may not always be easily discernible, and species use different strategies to deal with annual oscillation in environmental variables. In this comparative study carried out in New Zealand snapper (Chrysophrys auratus) and yellow-eyed mullet (Aldrichetta forsteri) were exposed to seasonal conditions for 12 months under an ad libitum feeding regime to investigate whether an unrestricted diet can produce a clear seasonal response in their growth profile and, assuming that food is limiting in the wild, what would be their maximum potential growth rates. Data showed a strong seasonal effect on growth parameters and energy partitioning in snapper, whereas there were no seasonal dependent responses in mullet. Snapper showed exponential growth during the warm period and the opposite was evident in winter when growth ceased and become even negative. Mullet grew steadily all year around with only a slight deflection from the linear growth trajectory in winter. Snapper’s maximum growth rates corresponded with the highest ambient temperature in the peak of summer. Therefore, this study was not able to determine the maximum potential growth rates for snapper as it would possibly increase with further temperature rise. In contrast, mullet appeared to grow fastest at ∼17/18 °C. In terms of fish condition – snapper partitioned resources to maximise winter survival by switching from investment into growth to energy stores on transition between autumn and winter, whereas yellow-eyed mullet focused on maximising accumulation of visceral fat to reach optimal levels of ∼15 % body mass, which was independent of environmental temperature. Results from this study suggest that wild length-based growth rates in mullet may indeed be feed limited, whereas this cannot be suggested for wild snapper.

Improving performance of AHU using exhaust air potential by applying exergy analysis

In this study, the exergy analysis of an AHU equipped with a heat and exergy recovery unit was investigated. The equations obtained from energy and exergy balance were solved based on a program developed in engineering equation solver. Through the air-to-air heat exchanger, the energy is transferred from the fresh air to the exhaust one but the exergy is transferred from the exhaust air to the fresh one. Therefore, the cooling coil power consumption and irreversibility were reduced. The efficacy of installing an air-to-air heat exchanger is dependent on the temperature and relative humidity of the ambient. Based on the results, at the lowest ambient temperature and relative humidity, the power consumption is reduced by 10.8%, while in the highest ambient temperature and relative humidity, this figure was 33%. Under ambient conditions with low temperatures and high relative humidity, installation of heat recovery unit reduced the irreversibility by 5.18%, while in the highest temperature and lowest relative humidity this figure was 12.8%.

Desalination of Seawater Using Lab Scale Solar Plant

The current study describes the desalination of sea water using solar energy with particular focus on the design and fabrication aspects for single slope solar still. The purpose of this study was to present a novel, economically feasible methodology along with the equipment to overcome the water shortage particularly in the remote areas along the coastal belt in Pakistan. In order to achieve these objectives, a laboratory scale solar still was fabricated made of galvanized iron having basin area of 5490 cm2 (length of 90 cm and width of 61 cm), front height 15 cm and back height 32 cm. The Inclined angle was kept at 15o. The experiments were conducted during typical winter days. Results showed that when the highest ambient temperature was 29.9 °C, the maximum value of the average solar intensity was 1,080 W/m2. A remarkable decrease in terms of total suspended solids (TSS), total dissolved solids (TDS), thermal conductivity, hardness, turbidity, and pH was observed. The value of TDS decreased from 29,100 mg/L to 385 mg/L, TSS from 0.07 g/100mL to 0.00086 g/mL, thermal conductivity from 45,500 μs to 595μs, hardness 133 meq/L to 2.7 meq/L, turbidity from 29.3 NTU to 19.3 NTU, and pH from 9.36 to 6.22, respectively. Furthermore, temperature profile against the intensity was drawn to identify the peak efficient hours with highest heat intensity. The suggested technique cannot only give a solution for the domestic level use rather it can be utilized in commercial scale in solar desalination facilities.

Desalination of Seawater Using Lab Scale Solar Plant

The current study describes the desalination of sea water using solar energy with particular focus on the design and fabrication aspects for single slope solar still. The purpose of this study was to present a novel, economically feasible methodology along with the equipment to overcome the water shortage particularly in the remote areas along the coastal belt in Pakistan. In order to achieve these objectives, a laboratory scale solar still was fabricated made of galvanized iron having basin area of 5490 cm2 (length of 90 cm and width of 61 cm), front height 15 cm and back height 32 cm. The Inclined angle was kept at 15o. The experiments were conducted during typical winter days. Results showed that when the highest ambient temperature was 29.9 °C, the maximum value of the average solar intensity was 1,080 W/m2. A remarkable decrease in terms of total suspended solids (TSS), total dissolved solids (TDS), thermal conductivity, hardness, turbidity, and pH was observed. The value of TDS decreased from 29,100 mg/L to 385 mg/L, TSS from 0.07 g/100mL to 0.00086 g/mL, thermal conductivity from 45,500 μs to 595μs, hardness 133 meq/L to 2.7 meq/L, turbidity from 29.3 NTU to 19.3 NTU, and pH from 9.36 to 6.22, respectively. Furthermore, temperature profile against the intensity was drawn to identify the peak efficient hours with highest heat intensity. The suggested technique cannot only give a solution for the domestic level use rather it can be utilized in commercial scale in solar desalination facilities.

Passive thermal management of a simulated battery pack at different climate conditions

This study contains a systematic investigation of RT-44 and GNP/RT-44 composite performance in passive thermal management of a battery pack operating at different climate temperatures. The thermal characterization of RT-44 and GNP/RT-44 composites was also carried out. For 7% GNP/RT-44 composite, solid phase and liquid phase thermal conductivities were enhanced by 230% and 130%, respectively. On the other hand, loss of energy storage capacity is about 7.5% compared to RT-44. During the passive thermal management, the temperature increase of battery was significantly reduced by RT-44 due to their sensible and latent energy storage capability. This superior performance is further enhanced by the increased thermal conductivity of 7% GNP/RT-44 composites. At the highest discharge rate (3.90 W) and at the highest ambient temperature (30 °C), the effective thermal protection duration was extended as 1.96 and 7.90 times compared to RT-44 and natural convection cases. Moreover, it is further extended by the reduction both the discharge rate and ambient temperatures. 7% GNP/RT-44 also reduced the maximum temperature difference within the battery pack at low ambient temperatures. On the other hand, RT-44 performed better maximum temperature difference at higher ambient temperatures due to phase change and constant temperature plateau effect.

Effect of Solar Radiation and Wind Speed on the Performance of Solar Dryer

This paper is to determine the effect of solar radiation and wind speed on the performance of solar dryers. The solar drying system uses solar radiation to dry agricultural products put on it. From the test carried out, it’s revealed that the solar dryer can perform more efficiently in the drying system. The Indian standard method of testing solar thermal was adopted. From the result it was observed that the highest ambient temperature was 400C, the wind speed was 3.7m/s and the solar radiation was 944.1W/m2. For further research, candle wax should be used which can also fasten the rate of drying agricultural products and also investigate the performance of the solar dryers.

Seawater desalination with solar-energy-integrated vacuum membrane distillation system

This study designed and tested a novel type of solar-energy-integrated vacuum membrane distillation (VMD) system for seawater desalination under actual environmental conditions in Wuhan, China. The system consists of eight parts: a seawater tank, solar collector, solar cooker, inclined VMD evaporator, circulating water vacuum pump, heat exchanger, fresh water tank, and brine tank. Natural seawater was used as feed and a hydrophobic hollow-fiber membrane module was used to improve seawater desalination. The experiment was conducted during a typical summer day. Results showed that when the highest ambient temperature was 33 °C, the maximum value of the average solar intensity was 1,080 W/m2. The system was able to generate 36 kg (per m2 membrane module) distilled fresh water during 1 day (7:00 am until 6:00 pm), the retention rate was between 99.67 and 99.987%, and electrical conductivity was between 0.00276 and 0.0673 mS/cm. The average salt rejection was over 90%. The proposed VMD system shows favorable potential application in desalination of brackish waters or high-salt wastewater treatment, as well.

Hourly dynamic simulation of solar ejector cooling system using TRNSYS for Jordanian climate

This work describes a simulation program developed on the TRNSYS-EES softwares. This program is used to design the solar collector subsystem components and to evaluate the performance of the solar ejector cooling system with R134a as a refrigerant. In addition dynamic hourly simulation of 7kW solar ejector cooling system (SECS) constant pressure mixing components, using TRNSYS software is carried out. The performance of solar collector and the overall system performance are investigated and the ejector sub-system is modeled with EES software.The solar collector type, area, storage tank size, and the flow rate through the cycle are optimized. Solar collector type and area are selected based on the maximum energy gain, where the maximum energy gain is a measure of the collector performance. The system performance is computed in the form of desired outlet temperature to run 7kW cooling cycle. The effect of tilt angle on the solar system performance is investigated and the optimum tilt angle for the best performance of the system is determined. Selection of the best refrigerant to meet the cooling requirement with the maximum COP is studied. In addition, the time fraction of the storage tank outlet temperature for different collector areas, at a mass flow rate of 50kg/hm2 is investigated. It is found that evacuated tube type has better performance than the flat plate type, where each collector is anchored at its optimal tilt angle of 28°. Furthermore, the energy required of the 7kW-cooling-system is adequately met with the selection of an evacuated-tube solar collector system with an area of 60–70m2. The solar fraction is in the range of 0.52–0.542 and the corresponding time fraction is 5.04h/days. Hourly and monthly simulation of SECS, which is supplemented with 2m3 storage tank size and operated at a flow rate of 50kg/h per square meter of collector area is carried out. Under peak solar radiation and highest ambient temperature, the overall system efficiency has a minimum value of 0.32, whereas the COPejec of the ejector cooling cycle for this model is in the range of 0.52–0.547, the solar collector efficiency is between 0.52 and 0.92, and the overall COPo is in the range of 0.32–0.47.

Is Soaking Cows During Dry Period an Effective Management Tool to Reduce Heat Stress and Improve Pospartum Productivity?

Avendaño-Reyes, L., Alvarez-Valenzuela, F.D., Correa-Calderón, A., Fadel, J.G. and Robinson, P.H. 2008. Is soaking cows during dry period an effective management tool to reduce heat stress and improve pospartum productivity? J. Appl. Anim. Res., 34: 97–100. In order to determine the effect of a cooling system on prepartum physiological parameters and postpartum productivity, forty multiparous Holstein cows were assigned to one of two treatments 60 days prior to their expected calving date: cooled (soaking for 2 min twice daily) and non-cooled. The highest ambient temperature registered during the study was 49.5C and the average daily temperature humidity index was higher than 72. Cooled cows showed a trend (P=0.08) to reduce their respiration rate, however, rectal temperature, body condition score and body weight were not affected at all (P>0.05). Postpartum milk yield, milk fat and milk energy output did not show significant differences, nor reproduction parameters postpartum (P>0.05). Thus soaking Holstein cows during the prepartum period had no advantage on postpartum productivity under hot and dry conditions.