The Theoretical and Experimental Researches on a Kind of Dew Point Indirect Evaporative Cooler

2012 ◽  
Vol 550-553 ◽  
pp. 2685-2689 ◽  
Author(s):  
Bao Hong Wang ◽  
Zhong Bao Liu ◽  
Jin Ju Cui
Keyword(s):  
Relative Humidity ◽  
Low Temperature ◽  
Positive Relationship ◽  
Experimental System ◽  
Dew Point ◽  
Inlet Temperature ◽  
Cooling Efficiency ◽  
Evaporative Cooler ◽  
Secondary Air ◽  
Experimental Researches

This paper designs a novel dew point indirect evaporative cooler. An experimental system of dew point indirect evaporative cooler is built up, The experimental results indicate that temperature of the primary air and the dew point efficiency have a positive relationship with the inlet temperature and relative humidity. Generally, in order to meet the blowing air requirements, maintain the high cooling efficiency and low temperature of the outlet air, the velocity of primary air should be 3m / s and the rate of primary and secondary air should be 1.5:1. When the flux of water is 3L/min the dew point efficiency is highest. In addition, the cooling effect was less affected by the temperature of the water.

The Cause and Forecasting of Ice Fogs *

1953 ◽  
Vol 34 (9) ◽  
pp. 397-400 ◽  
Author(s):  
H. Appleman
Keyword(s):  
Relative Humidity ◽  
Low Temperature ◽  
Combustion Process ◽  
Hydrocarbon Fuels ◽  
Dew Point ◽  
The Other ◽  
Sudden Increase ◽  
Minimum Frequency ◽  
Ice Fog ◽  
Rare Phenomenon

Studies carried out in Alaska and Canada have shown that fog is a relatively rare phenomenon at temperatures between 0° and − 30°F, with a minimum frequency between − 20° and −30°. At still lower temperatures, however, the frequency of fog increases rapidly. This effect is noted only in the immediate vicinity of inhabited areas, such as towns and airfields. The reason for the sudden increase in fog frequency at these temperatures, and the rarity or lack of fog at the higher temperatures, has not been heretofore explained. In a recent study on aircraft condensation trails, it was shown that if the temperature is sufficiently low (between − 20 and − 40°F, depending on the relative humidity), the burning of hydrocarbon fuels, such as would occur in towns and at airfields, easily results in supersaturation of the air and a “surface contrail” or ice fog. At higher temperatures, on the other hand, combustion actually reduces the relative humidity of the atmosphere, hindering the formation of fog. In this paper it is shown that low-temperature (ice) fogs form as a result of the combustion process, and curves are presented showing the temperature-dew-point relationship necessary for the formation of such fogs.

Experimental Study of a Novel Indirect Evaporative Cooler

2013 ◽  
Vol 671-674 ◽  
pp. 2547-2550
Author(s):  
Yu Gang Wang ◽  
Jia Ping Liu ◽  
Huang Xiang
Keyword(s):  
Experimental Study ◽  
Dew Point ◽  
Test Bed ◽  
Point Temperature ◽  
Dew Point Temperature ◽  
Air Volume ◽  
Cooling Section ◽  
Evaporative Cooler ◽  
Secondary Air ◽  
Set Up

Set up a test-bed, test the pre-cooling section, cooling section, and the units consist of them separately, then analysis the data. Within the experimental range, the best ratio of the secondary air volume and the primary air volume is 1.2 for the pre-cooling section, for the cooling section is 1.69. The outlet air temperature is below its wet bulb temperature for the units, and higher than its dew point temperature.

scholarly journals Numerical Investigation of a Novel Plate-Fin Indirect Evaporative Cooling System Considering Condensation

Processes ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 332
Author(s):  
Yuanyuan Zhou ◽  
Zhen Yan ◽  
Ming Gao ◽  
Qiumin Dai ◽  
Yanshun Yu
Keyword(s):  
Heat Transfer ◽  
Cooling System ◽  
Evaporative Cooling ◽  
Operating Conditions ◽  
Dew Point ◽  
Inlet Temperature ◽  
Thermoelectric Cooling ◽  
Evaporative Cooling System ◽  
Evaporative Cooler ◽  
Indirect Evaporative Cooling

An indirect evaporative cooling system combining with thermoelectric cooling technology (i.e., TIEC system) is proposed, in which a counter-flow plate-fin indirect evaporative cooler is inserted with thermoelectric cooling (i.e., TEC) modules. In hot and humid climate, condensation may occur on the dry channel surface of the cooler. For the TIEC system, with the aid of TEC technology, the surface temperature of the dry channel can be much lower than that of a traditional indirect evaporative cooler, thus, the condensation from the primary air is more likely to take place. A numerical model of this novel TIEC system is developed with specifically taking condensation from primary air into account. Detailed performance analysis of the TIEC system is carried out. Analytical results found that the condensation from primary air reduces the dew point effectiveness by up to 45.0% by weakening the sensible heat transfer but increases the coefficient of performance by up to 62.2% by increasing the latent heat transfer, under given conditions. The effects of main operating conditions, such as the electrical current I and number n of TEC modules, inlet temperature Tp,i, humidity ratio RHp and velocity Vp of the primary air, and the mass flow rate ratio x of secondary to primary air, are investigated under non-condensation and condensation states. It is shown that condensate is more easily produced under higher I, n, Tp,i, RHp, x and lower Vp.

scholarly journals Solar Radiation, Air Temperature, Relative Humidity, and Dew Point Study: Damak, Jhapa, Nepal

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Arun Kumar Shrestha ◽  
Arati Thapa ◽  
Hima Gautam
Keyword(s):  
Relative Humidity ◽  
Solar Radiation ◽  
Air Temperature ◽  
Gaussian Function ◽  
Great Influence ◽  
Dew Point ◽  
Upward Trend ◽  
Summer Maximum ◽  
Online Calculator ◽  
Climatic Phenomenon

Monitoring and prediction of the climatic phenomenon are of keen interest in recent years because it has great influence in the lives of people and their environments. This paper is aimed at reporting the variation of daily and monthly solar radiation, air temperature, relative humidity (RH), and dew point over the year of 2013 based on the data obtained from the weather station situated in Damak, Nepal. The result shows that on a clear day, the variation of solar radiation and RH follows the Gaussian function in which the first one has an upward trend and the second one has a downward trend. However, the change in air temperature satisfies the sine function. The dew point temperature shows somewhat complex behavior. Monthly variation of solar radiation, air temperature, and dew point shows a similar pattern, lower at winter and higher in summer. Maximum solar radiation (331 Wm-2) was observed in May and minimum (170 Wm-2) in December. Air temperature and dew point had the highest value from June to September nearly at 29°C and 25°C, respectively. The lowest value of the relative humidity (55.4%) in April indicates the driest month of the year. Dew point was also calculated from the actual readings of air temperature and relative humidity using the online calculator, and the calculated value showed the exact linear relationship with the observed value. The diurnal and nocturnal temperature of each month showed that temperature difference was relatively lower (less than 10°C) at summer rather than in winter.

scholarly journals Influence of relative humidity and low temperature hydrothermal degradation on fretting wear of Y-TZP dental ceramics

Wear ◽  
2019 ◽  
Vol 428-429 ◽  
pp. 1-9 ◽  
Author(s):  
Amparo Borrell ◽  
Lorena Gil ◽  
Alvaro Presenda ◽  
Maria D. Salvador ◽  
Jozef Vleugels ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Low Temperature ◽  
Fretting Wear ◽  
Dental Ceramics ◽  
Hydrothermal Degradation

Characterization of an Isolated Hybrid Cooled Server With Failure Scenarios Using Warm Water Cooling

2017 ◽  
Author(s):  
Uschas Chowdhury ◽  
Manasa Sahini ◽  
Ashwin Siddarth ◽  
Dereje Agonafer ◽  
Steve Branton
Keyword(s):  
Energy Consumption ◽  
Data Centers ◽  
Cooling System ◽  
Warm Water ◽  
Alternative Methods ◽  
Inlet Temperature ◽  
Cooling Efficiency ◽  
Water Cooling ◽  
Liquid Cooling ◽  
Total Energy Consumption

Modern day data centers are operated at high power for increased power density, maintenance, and cooling which covers almost 2 percent (70 billion kilowatt-hours) of the total energy consumption in the US. IT components and cooling system occupy the major portion of this energy consumption. Although data centers are designed to perform efficiently, cooling the high-density components is still a challenge. So, alternative methods to improve the cooling efficiency has become the drive to reduce the cooling cost. As liquid cooling is more efficient for high specific heat capacity, density, and thermal conductivity, hybrid cooling can offer the advantage of liquid cooling of high heat generating components in the traditional air-cooled servers. In this experiment, a 1U server is equipped with cold plate to cool the CPUs while the rest of the components are cooled by fans. In this study, predictive fan and pump failure analysis are performed which also helps to explore the options for redundancy and to reduce the cooling cost by improving cooling efficiency. Redundancy requires the knowledge of planned and unplanned system failures. As the main heat generating components are cooled by liquid, warm water cooling can be employed to observe the effects of raised inlet conditions in a hybrid cooled server with failure scenarios. The ASHRAE guidance class W4 for liquid cooling is chosen for our experiment to operate in a range from 25°C – 45°C. The experiments are conducted separately for the pump and fan failure scenarios. Computational load of idle, 10%, 30%, 50%, 70% and 98% are applied while powering only one pump and the miniature dry cooler fans are controlled externally to maintain constant inlet temperature of the coolant. As the rest of components such as DIMMs & PCH are cooled by air, maximum utilization for memory is applied while reducing the number fans in each case for fan failure scenario. The components temperatures and power consumption are recorded in each case for performance analysis.

Sustainable Poultry House Ventilation Using Dew Point Indirect Evaporative Cooler Aided With Radiative Cooling

2021 ◽  
Author(s):  
Douaa Al-Assaad ◽  
Nesreen Ghaddar ◽  
Kamel Ghali ◽  
Djamel Ouahrani
Keyword(s):  
Air Quality ◽  
Distribution System ◽  
Thermal Environment ◽  
Cross Flow ◽  
Production Quality ◽  
Dew Point ◽  
Radiative Cooling ◽  
Poultry House ◽  
Evaporative Cooler ◽  
June July

Abstract Maintaining good production quality in layer poultry houses is directly correlated to the thermal environment of the laying hens as well as their breathable air quality. This work compares the performance of two passive cooling systems in meeting the thermal and indoor air quality requirements (CO2, water vapor and NH3) in a layer house in Doha, Qatar characterized by a semi-arid climate. The first system is a standalone cross flow dew point evaporative cooler (DPIEC) supplying air through a localized air distribution system. The second system is a DPIEC aided by a radiative cooling (RC) panel that pre-cools the supply fresh air, in an effort to reduce the system sizing, air and water consumption even further. To achieve these objectives, a modular analysis was adopted, where mathematical models were developed for the DPIEC and RC systems and the poultry house module conditioned by the localized system. A 3D CFD model was developed for the compartment conditioned by the localized system. The DPIEC was sized and the hourly variation in needed supply fresh air and water was determined for the critical month of May, June July of the summer season.

Changes in Aerobic Plate and Escherichia coli–Coliform Counts and in Populations of Inoculated Foodborne Pathogens on Inshell Walnuts during Storage

2016 ◽  
Vol 79 (7) ◽  
pp. 1143-1153 ◽  
Author(s):  
JOHN C. FRELKA ◽  
GORDON R. DAVIDSON ◽  
LINDA J. HARRIS
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Relative Humidity ◽  
Low Temperature ◽  
Foodborne Pathogens ◽  
Limit Of Detection ◽  
Sampling Time ◽  
E Coli ◽  
Plate Counts ◽  
Forced Air

ABSTRACT After harvest, inshell walnuts are dried using low-temperature forced air and are then stored in bins or silos for up to 1 year. To better understand the survival of bacteria on inshell walnuts, aerobic plate counts (APCs) and Escherichia coli–coliform counts (ECCs) were evaluated during commercial storage (10 to 12°C and 63 to 65% relative humidity) over 9 months. APCs decreased by 1.4 to 2.0 log CFU per nut during the first 5 months of storage, and ECCs decreased by 1.3 to 2.2 log CFU per nut in the first month of storage. Through the remaining 4 to 8 months of storage, APCs and ECCs remained unchanged (P > 0.05) or decreased by <0.15 log CFU per nut per month. Similar trends were observed on kernels extracted from the inshell walnuts. APCs and ECCs were consistently and often significantly higher on kernels extracted from visibly broken inshell walnuts than on kernels extracted from visibly intact inshell walnuts. Parameters measured in this study were used to determine the survival of five-strain cocktails of E. coli O157:H7, Listeria monocytogenes, and Salmonella inoculated onto freshly hulled inshell walnuts (~8 log CFU/g) after simulated commercial drying (10 to 12 h; 40°C) and simulated commercial storage (12 months at 10°C and 65% relative humidity). Populations declined by 2.86, 5.01, and 4.40 log CFU per nut for E. coli O157:H7, L. monocytogenes, and Salmonella, respectively, after drying and during the first 8 days of storage. Salmonella populations changed at a rate of −0.33 log CFU per nut per month between days 8 and 360, to final levels of 2.83 ± 0.79 log CFU per nut. E. coli and L. monocytogenes populations changed by −0.17 log CFU per nut per month and −0.26 log CFU per nut per month between days 8 and 360, respectively. For some samples, E. coli or L. monocytogenes populations were below the limit of detection by plating (0.60 log CFU per nut) by day 183 or 148, respectively; at least one of the six samples was positive at each subsequent sampling time by either plating or by enrichment.

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