scholarly journals Functional Performance Evaluation of a Novel Thermal Environment Sensor Array

2018 ◽  
Vol 61 (3) ◽  
pp. 1077-1088
Author(s):  
Brett C. Ramirez ◽  
Yun Gao ◽  
Steven J. Hoff ◽  
Jay D. Harmon
Keyword(s):  
Data Acquisition ◽  
Heat Loss ◽  
Sensor Array ◽  
Functional Performance ◽  
Thermal Environment ◽  
Reference Conditions ◽  
Total Heat ◽  
Total Heat Loss ◽  
Substantial Impact ◽  
Heat Transfer Theory

Abstract. The thermal environment (TE) inside livestock and poultry facilities has a substantial impact on animal growth performance and facility energy usage; therefore, the TE must be quantified correctly to maintain the optimal TE that maximizes feed efficiency and consumes minimal resources. To achieve this goal, a TE sensor array (TESA) and accompanying data acquisition system were previously developed to measure dry-bulb temperature (tdb), black globe temperature, airspeed, and relative humidity (RH). While measurement of each parameter is useful individually, it is more informative when they are combined to estimate and assess the total impact that the TE has on an animal. Hence, the objectives of this study were to (1) design, construct, and commission a TE simulation system, named the Animal Thermal Environment Replication and Measurement System (AThERMS), and (2) compare total sensible heat loss estimated by TESA to a reference ideal temperature source (ITS) when subjected to different TE conditions inside AThERMS. AThERMS is a 1.04 × 1.17 × 1.04 m chamber inside a large insulated enclosure in which air supplied by an air handling unit provides unique combinations of tdb, RH, and airspeed while independently controlling chamber surface temperature (ts). Commissioning of AThERMS included qualitative (smoke visualization) and quantitative (three-dimensional traverse) velocity characterizations in the central region of the chamber and verification of similar and stable ts for all six surfaces. Analysis of velocity contours at three nominal flow rates indicated steady patterns, and at three nominal ts values (13°C, 23°C, and 33°C) during 2 h steady-state operation, the maximum average difference between any two of the six surface ts values was 0.26°C. The TESA was then suspended in AThERMS adjacent to the ITS (15.24 cm diameter black copper sphere with a heater immersed in water). The ITS and TESA were subjected to two nominal airspeeds (~0.5 and 2.0 m s-1) at three nominal tdb values (17°C, 25°C, and 33°C) with a mean radiant temperature approximately equal to the nominal tdb. Total heat loss was estimated from heat transfer theory with TESA measurements as inputs and compared to the measured root mean square power required to maintain a constant water temperature in the ITS. Overall, predicted total heat loss underestimated measured power for all six tests. Future work needs to improve the measurement accuracy at low total heat losses. AThERMS can be used to simulate different TEs that an animal may experience and provide steady reference conditions to verify TE measurements. The TESA is a novel and effective tool for understanding the TE distribution and estimating total heat loss. Keywords: Black globe, Data acquisition, Swine, Ventilation.

Cavity receiver thermal performance analysis based on total heat loss coefficient and efficiency factor

2018 ◽  
Vol 42 (6) ◽  
pp. 2284-2289 ◽  
Author(s):  
Qiangqiang Zhang ◽  
Xin Li ◽  
Zhifeng Wang ◽  
Zhi Li ◽  
Hong Liu ◽  
...  
Keyword(s):  
Performance Analysis ◽  
Heat Loss ◽  
Thermal Performance ◽  
Efficiency Factor ◽  
Loss Coefficient ◽  
Total Heat ◽  
Total Heat Loss

scholarly journals Fitness-related differences in the rate of whole-body total heat loss in exercising young healthy women are heat-load dependent

2018 ◽  
Vol 103 (3) ◽  
pp. 312-317 ◽  
Author(s):  
Dallon T. Lamarche ◽  
Sean R. Notley ◽  
Martin P. Poirier ◽  
Glen P. Kenny
Keyword(s):  
Heat Loss ◽  
Heat Load ◽  
Total Heat ◽  
Whole Body ◽  
Total Heat Loss ◽  
Healthy Women

scholarly journals Heat loss analysis of three coil cylindrical solar cavity receiver of parabolic dish for process heat

2019 ◽  
Vol 23 (Suppl. 4) ◽  
pp. 1301-1310
Author(s):  
Ramola Sinha ◽  
Nitin Gulhane ◽  
Jan Taler ◽  
Pawel Oclon
Keyword(s):  
Cost Effectiveness ◽  
Heat Loss ◽  
Total Heat ◽  
Fluid Temperature ◽  
Total Heat Loss ◽  
Wall Area ◽  
Single Coil ◽  
Receiver System ◽  
Parabolic Dish ◽  
Process Heat

The share of solar thermal energy for process heat at sub cooled temperature is estimated about 30% of the total demand. The assessment of heat loss from tubular receiver used for the process heat is necessary to improve the thermal efficiency and consequently the cost effectiveness of the parabolic dish receiver system. The study considers a modified three coil solar cavity receiver of wall area three times (approximately) as compared to the existing single coil receiver and experimentally investigates the effect of increases in cavity inner wall area, fluid inlet temperature (50-75?C), and cavity inclination angle (? = 0-90?) on the combined (total) heat loss from receiver under no wind condition. This paper also develops an analytical model to estimate the different mode of heat losses from the downward facing receiver. In the mean fluid temperature range of 50?C to 70?C, the total heat loss from three coil receiver is reduced up to 40.98% at 90? and 20% at 0? inclination, as compared to single coil receiver. The analytical modeling estimates very low heat loss from conduction (1-3%) and radiation (2-8%) and high heat loss from convection (97-89%). The heat loss by natural convection decreases sharply with increase in cavity inclination, while the heat loss by radiation and conduction increases slowly with inclination. A three coil cavity receiver might be considered in the design to reduce heat loss from parabolic dish receiver system to improve the thermal performance and cost effectiveness.

A Comparative Numerical Study on Conjugate Natural Convection From Vertical Hollow Cylinder With Finite Thickness Placed on Ground and in Air

2020 ◽  
Vol 13 (2) ◽  
Author(s):  
Manoj Kumar Dash ◽  
Sukanta Kumar Dash
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Natural Convection ◽  
Heat Loss ◽  
Hollow Cylinder ◽  
Average Nusselt Number ◽  
Total Heat ◽  
Outer Diameter ◽  
Thermal Plume ◽  
Total Heat Loss

Abstract The present work reports a comparative analysis of natural convection heat transfer from a thick hollow vertical cylinder either placed on the ground or suspended in the air. The numerical simulations have been performed by varying the cylinder length to its outer diameter (L/Do) in the range of 0.2–20, the thickness ratio (Di/Do) in a range of 0.5–0.9, and Rayleigh number (Ra) from 104 to 108. The flow and heat transfer characteristics have been delineated precisely with the presentation of the thermal plume and flow field in the vicinity of the cylinder. The variation of average Nusselt number (Nu), local Nu, and contribution to total heat loss from different surfaces with the pertinent parameters have been elucidated graphically. The average Nu is always more for the cylinder in the air compared with the case when it is on the ground. However, the difference between the Nu for these two cases diminishes, as the L/Do increases. It has also been found that the contribution to total heat loss from the inner surface of the hollow cylinder suspended in air increases with L/Do, attains a peak, and decreases sharply. Cooling time curves for the cylinder placed in air or on the ground have been described precisely. Finally, a correlation for the average Nusselt number as a function of all the pertinent parameters has been proposed that can be useful for industrial and academic purposes.

scholarly journals Self-reported physical activity level does not alter whole-body total heat loss independently of aerobic fitness in young adults during exercise in the heat

2019 ◽  
Vol 44 (1) ◽  
pp. 99-102 ◽  
Author(s):  
Dallon T. Lamarche ◽  
Sean R. Notley ◽  
Martin P. Poirier ◽  
Glen P. Kenny
Keyword(s):  
Physical Activity ◽  
Young Adults ◽  
Oxygen Consumption ◽  
Heat Loss ◽  
Aerobic Fitness ◽  
Total Heat ◽  
Activity Level ◽  
Peak Oxygen Consumption ◽  
Whole Body ◽  
Total Heat Loss

We evaluated whether self-reported physical activity (PA) level modulates whole-body total heat loss (WB-THL) as assessed using direct calorimetry in 10 young adults (aged 22 ± 3 years) matched for rate of peak oxygen consumption (an index for aerobic fitness), but of low and high self-reported PA, during 3 incremental cycling bouts (∼39%, 52%, and 64% peak oxygen consumption) in the heat (40 °C). We showed that level of self-reported PA does not appear to influence WB-THL independently of peak oxygen consumption.

scholarly journals The Wind Test on Heat Loss from Three Coil Cavity Receiver for a Parabolic Dish Collector

2019 ◽  
Vol 128 ◽  
pp. 01006 ◽  
Author(s):  
Ramola Sinha ◽  
Nitin P. Gulhane ◽  
Paweł Ocłoń ◽  
Jan Taler ◽  
Rahimi Gorji
Keyword(s):  
Heat Loss ◽  
Total Heat ◽  
Inlet Temperature ◽  
Fluid Temperature ◽  
Wind Condition ◽  
Horizontal Position ◽  
Total Heat Loss ◽  
Maximum Heat ◽  
Mean Temperature ◽  
Parabolic Dish

The heat loss from cavity receiver in parabolic dish system determines the efficiency and cost effectiveness of the system. A modified three coil solar cavity receiver of inner wall area approximately three times of single coil receiver, is experimentally investigated to study the effect of fluid inlet temperature (Tfi=50°C to 75 °C) and cavity inclination angle (θ = 0° to 90°) on the heat loss from receiver under wind condition for head on wind and side on wind velocity at 3 m/s. Overall it was found that the natural and forced convection total heat loss increases with increase in mean fluid temperature. The combined heat loss decreases sharply with the increase in cavity inclination and observed to be maximum for horizontal position of receiver and minimum with the receiver facing vertically downward for all investigations. The maximum heat lossin wind test (V=3m/s) is 1045 W at θ=0° cavity inclination at mean fluid temperature 68 °C and minimum at 173 W θ=90° at 53°C. Total heat loss from the receiver under wind condition (V=3m/s) is up to 25% higher(1.25 times at 0° inclination) than without wind at mean fluid temperature ~70°C and minimum 19.64 % (1.2 times at 90° inclination) in mean temperature ~50 °C . In horizontal position of the receiver (θ=0°), the totalheat loss by head on wind is about 1.23 times (18% higher ) as compared to side on wind (at fluid mean temperature ~ 70°C). For receiver facing downward (θ=90°), for head-on wind, total heat loss is approximately the same as that for side-on wind.

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