Functional Performance Evaluation of a Novel Thermal Environment Sensor Array

<abstract> <b>Abstract.</b> The Thermal Environment (TE) inside swine facilities has a substantial impact on animal performance and facility energy usage; therefore, proper control and measurement are required to maintain the optimal TE that maximizes performance and consumes minimal energy. Currently, controllers only monitor and describe the TE with dry-bulb temperature (t_db); however, t_db does not account for all the factors that influence the TE. Therefore, a novel Thermal Environment Sensor Array (TESA) network and accompanying data acquisition systems were developed for a preliminary investigation inside a commercial, ~800 hd, positive pressure ventilated, filtered breeding facility located in central Iowa. Data from the TESA network and from various ventilation system components from the installed controller would allow for control and distribution performance to be evaluated. Hence, the objectives of this research were: (1) evaluate the Thermal Environment Modification System (TEMS) controller response to seasonal and diurnal fluctuations; (2) implement and evaluate TESA and accompanying DAQ system performance; and (3) assess TE spatial uniformity across three pens. Six TESAs (two suspended per pen), each with: t_db, black globe temperature, airspeed, and relative humidity measurements were deployed since November 2015 to initially evaluate the performance and the robustness of this new system, as well as, explore the effectiveness and distribution of the facility‘s thermal environmental modification and control system. Overall, the TESAs performed well, except for some dust accumulation on the t_db and black globe sensors. Results showed that t_db inside the facility was within 1°C and 2°C of the set point 36.3% and 75.3% of the monitoring period, respectively. A maximum 10.6°C above the set point and 5.2°C below the set point were recorded. The preliminary findings from this study will be useful for developing functional performance tests to commission livestock and poultry facilities. These functional performance tests will analyze fan performance, heater distribution, TEMS controller abilities, spatiotemporal TE uniformity, etc. The information obtained will allow facility operators to make better management practices that ultimately decrease production costs and improve the thermal comfort for the animals.

Current occupational heat stress guidelines rely on time-weighted averaging to quantify the metabolic demands of variable-intensity work. However, variable-intensity work may be associated with impairments in whole-body total heat loss (dry + evaporative heat loss), especially in older workers, which exacerbate heat strain relative to constant-intensity work eliciting the same time-weighted average metabolic rate. We, therefore, used direct calorimetry to evaluate whether variable-intensity work would cause decrements in the average rate of whole-body total heat loss that augment body heat storage and core temperature compared with constant-intensity work in young and older men. Eight young (19-31 yr) and eight older (54-65 yr) men completed four trials involving 90 min of work (cycling) eliciting an average metabolic heat production of ~200 W·m in dry-heat (40°C, 20% relative humidity). One trial involved constant-intensity work (CON), whereas the others involved 10-min cycles of variable-intensity work: 5-min low-intensity and 5-min high-intensity (VAR 5:5), 6-min low-intensity and 4-min very high-intensity (VAR 6:4), and 7-min low- and 3-min very, very high-intensity (VAR 7:3). Metabolic heat production, total heat loss, body heat storage (heat production minus total heat loss), and core (rectal) temperature were measured throughout. When averaged over each 90-min work period, metabolic heat production, total heat loss, and heat storage were similar between groups and conditions (all P ≥ 0.152). Peak core temperature (average of final 10 min) was also similar between groups and conditions (both P ≥ 0.111). Whole-body total heat loss, heat storage, and core temperature were not significantly influenced by the partitioning of work intensity in young or older men, indicating that time-weighted averaging appears to be appropriate for quantifying the metabolic demands of variable-intensity work to assess occupational heat stress.

We examined the total heat loss, which is the summation of heat loss and evaporation loss, for the firefighters’ protective clothing and the combined clothing samples which were prepared from the firefighters’ protective clothing, the working wear clothing and the commercial T-shirts as determined by a test method specified in ASTM F 1868 part C. We compare the total heat loss, heat loss and evaporation loss obtained from firefighters’ protective clothing and combined clothing samples with those of the commercial T-shirts and a working wear using in a fire station. We confirmed that the total heat loss of firefighters’ protective clothing and combined clothing samples were approximately 2.5 times less and approximately 2.9 times less than those of clothing materials such as T-shirts and working wear clothing, respectively. It was found that very strong correlation existed between total heat loss and evaporation loss. We suggested that the total heat loss determined according to ASTM F 1868 part C could be estimated from the values of evaporation loss.

<b><sc>Abstract.</sc></b> A pilot-scale laboratory was designed and built to meet the specific needs of conducting precision livestock farming (PLF) research related to optimizing thermal environment. The two room (8.5 by 3.7 by 2.9 m; W by L by H) laboratory was built inside an existing structure utilizing common construction methods and materials. Each room was fully instrumented to characterize the thermal (dry-bulb temperature and relative humidity) and gaseous (O₂, CO₂) environment and facilitate both direct and indirect calorimetry measurements. The laboratory‘s instrumentation set-up allows for expansion into additional thermal (black-globe temperature), lighting analysis (wavelength and intensity) and gas (NH₃) as experiments demand. Ventilation was a “modified push-pull” style with one common supply fan and an exhaust fan for each room operating at a slight negative pressure. Each room also featured an airflow measurement device that was individually calibrated. The commissioning of the environmental control demonstrated all sensors were functioning correctly. This laboratory can be used for various poultry and swine experiments for developing and refining PLF technologies before advancing to field trials in commercial facilities. Unique and extensive research laboratories are needed to readily facilitate the research and development of PLF technologies related to characterizing and controlling the animal occupied zone thermal environment that align with industry needs. Traditional production facilities present challenges related to biosecurity, instrumentation capabilities, labor, and travel to remote sites.

Prolonged work in the heat may exacerbate the rise in core temperature on the next work day, especially in older workers who display impairments in whole-body heat loss that increase body heat storage and core temperature relative to young adults during heat stress. We therefore evaluated whether whole-body heat loss in older adults was impaired on the day after prolonged work in the heat. Whole-body heat exchange and heat storage were assessed in nine older (53-64 yr) men during three 30-min bouts of semirecumbent cycling at fixed rates of metabolic heat production (150 [Ex1], 200 [Ex2], 250 W·m [Ex3]), each separated by 15-min recovery, in hot-dry conditions (40°C, 20% relative humidity), immediately before (day 1), and on the day after (day 2) a prolonged, work simulation (~7.5 h) involving moderate-intensity intermittent exercise in hot-dry conditions (38°C, 34% relative humidity). Total heat loss (evaporative ± dry heat exchange) and metabolic heat production were measured using direct and indirect calorimetry, respectively. Body heat storage was quantified as the temporal summation of heat production and loss. Total heat loss (mean ± SD) during Ex1 did not differ between days 1 and 2 (151 ± 15 and 147 ± 14 W·m, respectively; P = 0.27), but was attenuated on day 2 during Ex2 (181 ± 15 W·m) and Ex3 (218 ± 16 W·m) relative to day 1 (192 ± 14 and 230 ± 19 W·m, respectively; both P < 0.01). Consequently, body heat storage throughout the protocol on day 2 (276 ± 114 kJ) was 31% greater than on day 1 (191 ± 87 kJ; P < 0.01). Prolonged work in the heat causes next-day impairments in whole-body heat loss, which exacerbate heat storage and may elevate the risk of heat injury on the following day in older workers.

Older adults commonly experience sleep deprivation, which has been observed to alter thermoregulatory function in young adults. This may exacerbate risks of heat-related injury and illness during heat stress, due to age-related reductions in heat loss capacity. However, whether sleep deprivation modulates thermoregulatory function in older adults remains unclear. Thus, we aimed to assess the impact 24 h of total sleep deprivation has on whole-body heat loss during exercise-heat stress in older adults. Following either a night of normal sleep or 24-h sleep deprivation, 10 older males (mean (SD); age 61 (4) yr) performed three 30-min exercise bouts at incrementally increasing rates of metabolic heat production (150, 200, 250 W·m -2 ), each separated by 15-min rest in hot, dry conditions (40°C, ~13% relative humidity). Whole-body total (dry + evaporative) heat loss and metabolic heat production were measured continuously using direct and indirect calorimetry, respectively, and used to calculate body heat storage. Peak whole-body total loss (mean difference (95% confidence interval), -12 (-20 to -3) W·m -2 ; P = 0.010) was reduced and body heat storage (0.60 (0.32 to 0.89) kJ·min -1 ; P = 0.002) increased during high-intensity exercise following sleep deprivation compared with normal sleep. However, evaporative heat loss (-10 (-20 to 1) W·m -2 ; P = 0.062) and dry heat gain (-2 (-9 to 5) W·m -2 ; P = 0.512) were not different between conditions. Sleep deprivation impaired whole-body total heat loss in older males, leading to greater heat storage during exercise-heat stress. Thus, sleep-deprived older adults performing prolonged high-intensity exercise in hot conditions may be at a heightened risk of heat-related illness or injury.

Galvanizing facilities are highly energy intensive operation with electrical and fuel energy representing a significant share of their total energy usage. Furnaces are extensively used in galvanizing process. Production process expertise along with the energy conservation practices can play a significant role in proper usage of energy at galvanizing facilities. Therefore, benchmarking galvanizing energy consumption and understanding the specific energy consumption by various elements are critical. E-GEPDSS (Enhanced Galvanizing Energy Profiler Decision Support System) was built to identify this specific energy consumption by using heat balance analysis. The use of E-GEPDSS does not hinder the production process and the user may run the model for different set of operating conditions and observe the results. The results obtained from the analysis will help the user to make energy enhancing decisions.;This research involved the analysis of galvanizing operations focusing on the furnace side of energy consumption. The furnace heat balance was built and applied using the data collected from a host company during the plant visit. Sensitivity analysis were done to study the impact of changing process and product parameters on the total heat loss from the system.;From the energy analysis conducted for the furnace equipment at the host facility, it was found that the useful heat absorbed by the product is only 50% of the heat supplied to the furnace and rest of heat dissipates as losses. Heat losses from surfaces, walls, water cooling and stack are significant. Heat loss due to opening and phase change heat loss seem not to be significant. Emissivity, dimensions of the furnace, temperature of the zones, thermal conductivity of insulation materials and the strip temperature at the entry and exit of each zone have significant impact on the total heat loss. In the future, the model will be applied extensively to more galvanizing lines in order to help the galvanizers to have a better understanding about the energy consumption while producing their product.

The influence of wind speed, aperture ratio and tilt angle on the heat losses from a finely controlled heated cavity for a solar receiver

1. The thermic effect of a glucose load (50 g) was studied in ten control and eleven obese female subjects, using both direct and indirect calorimetry simultaneously. Experiments were done under conditions of thermal equilbrium (28 degrees and 30% relative humidity). 2. Thermal balance (heat production measured by indirect calorimetry minus heat losses measured directly) was negative in the control group during the fasting period (heat deficit -14-2 +/- 5-0 kJ/m2 per h), whereas that of the obese group was in equilibrium (+ 1-4 +/- 4-8 kJ/m2 per h). 3. After the glucose load, metabolic rate increased 13-0 +/- 1-5 and 1-3% in the control and obese groups respectively. 4. In contrast to the metabolic rate, total heat losses were not significantly altered in either group after the glucose load. Total heat losses of the obese group were significantly lower than those of the control group throughout the experimental period. 5. During the experiments the amount of heat stored was increased in both groups. Thermal balance in the control group became positive while that of the obese group remained positive. 6. During the fasting period, the control subjects oxidized more carbohydrates (90-4 mg/min) than lipids (68-8 mg/min), whereas obese subjects oxidized more lipids (103-7 mg/min) than carbohydrates (50.2 mg/min). After the glucose load, the oxidation rate of carbohydrates was increased in both groups to 158-1 mg/min in control subjects and 95-6 mg/min in obese subjects. 7. The mean skin temperature of the control subjects was significantly higher than that of the obese subjects and remained higher throughout the postprandial period. 8. These results indicate that: (a) during the fasting period, the energy sources utilized and the thermal balance of the two groups were different; (b) the thermic effect of glucose was less in the obese subjects and, therefore, might be a factor contributing to their low energy expenditure.

Heat fluxes at the lake surface play an integral part in determining the energy budget and thermal structure in lakes, including regulating how lakes respond to climate change. We explore patterns in turbulent heat fluxes, which vary across temporal and spatial scales, using in situ high‐frequency monitoring data from 45 globally distributed lakes. Our analysis demonstrates that some of the lakes studied follow a marked seasonal cycle in their turbulent surface fluxes and that turbulent heat loss is highest in larger lakes and those situated at low latitude. The Bowen ratio, which is the ratio of mean sensible to mean latent heat fluxes, is smaller at low latitudes and, in turn, the relative contribution of evaporative to total turbulent heat loss increases toward the tropics. Latent heat transfer ranged from ~ 60% to &gt; 90% of total turbulent heat loss in the examined lakes. The Bowen ratio ranged from 0.04 to 0.69 and correlated significantly with latitude. The relative contributions to total turbulent heat loss therefore differ among lakes, and these contributions are influenced greatly by lake location. Our findings have implications for understanding the role of lakes in the climate system, effects on the lake water balance, and temperature‐dependent processes in lakes.

The aim of this study was to evaluate changes in total respiratory heat loss during use of a heat and moisture exchanger (HME) in tracheotomized patients. Tracheal humidity and temperature were measured before the application and during use of the HME (plastic foam impregnated with CaCl2), and total respiratory heat loss was calculated. No significant difference was found between the convective heat exchange before and after use of the HME for a 10-minute period. When the HME was placed on the tracheal opening, the evaporative heat exchange and the total respiratory heat loss decreased significantly. The results indicate that passive airway humidification is effective in tracheotomized patients even after a 10-minute period. However, the positive effect on the energy balance of the tracheal mucosa after prolonged use of the HME remains to be proven.

The silvopastoral system has the potential to alleviate the negative impacts of heat stress on livestock. Through a preliminary study, we assessed the thermal environment experienced by hair coat lambs, as well as the impacts on their bio-thermal and behavioural responses, when either kept in either the silvopastoral system, or exposed to full sun. Twelve hair coat lambs (Dorper × Santa Ines) were randomly assigned to a silvopastoral system or full sun exposure during the summer (from January to February 2017). Parameters, including air temperature, black globe temperature, relative humidity, wind speed, and ground surface temperature, were measured daily for both thermal environments. From 14:00 to 16:00, lambs kept in silvopastoral areas experienced lower levels of air temperature, radiant heat load, and ground surface temperature. Consequently, they had a lower hair coat surface and lower body rectal temperatures. Lambs exposed to a shaded environment spent more time grazing and walking, and less time standing at rest. In conclusion, lambs kept in a silvopastoral system experienced lower levels of radiant heat load and ground surface temperature. In addition, the animals showed a reduced requirement for evaporative cooling and expressed behaviours that indicated a comfortable thermal environment.

The objective of this study was to examine the effect of ingested water temperature on heat balance during exercise as assessed by direct calorimetry. Ten healthy males (25 ± 4 yr) cycled at 50% V˙O2peak (equivalent rate of metabolic heat production (M-W) of 523 ± 84 W) for 75 min under thermocomfortable conditions (25°C, 25% relative humidity) while consuming either hot (50°C) or cold (1.5°C) water. Four 3.2 mL·kg⁻¹ boluses of hot or cold water were consumed 5 min before and at 15, 30, and 45 min after the onset of exercise. Total heat loss (HL = evaporative heat loss (HE) ± dry heat exchange (HD)) and M-W were measured by direct and indirect calorimetry, respectively. Change in body heat content (ΔHb) was calculated as the temporal summation of M-W and HL and adjusted for changes in heat transfer from the ingested fluid (Hfluid). The absolute difference for HL (209 ± 81 kJ) was similar to the absolute difference of Hfluid (204 ± 36 kJ) between conditions (P = 0.785). Furthermore, the difference in HL was primarily explained by the corresponding changes in HE (hot: 1538 ± 393 kJ; cold: 1358 ± 330 kJ) because HD was found to be similar between conditions (P = 0.220). Consequently, no difference in ΔHb was observed between the hot (364 ± 152 kJ) and cold (363 ± 134 kJ) conditions (P = 0.971) during exercise. We show that ingestion of hot water elicits a greater HL relative to cold water ingestion during exercise. However, this response was only compensated for the heat of the ingested fluid as evidenced by similar ΔHb between conditions. Therefore, our findings indicate that relative to cold water ingestion, consuming hot water does not provide a thermoregulatory advantage. Both hot and cold water ingestion results in the same amount of heat stored during prolonged moderate-intensity exercise.

Extract: The thermal balance of 22 full term, 9 small for date, and 8 large premature infants was studied by gradient layer direct calorimetry on the 1st day of life. In addition, the influence of muscular activity on the ability to sweat of 8 full term infants was investigated. The same measurements were repeated in 20 infants on the 3rd day of life. All infants were subjected to the same experimental conditions: ambient temperature 37°, relative humidity 50%, and air flow 30 liters/min. It was demonstrated that the evaporation of water was the primary way to dissipate heat in a heat-gaining environment. Active thermoregulatory sweating was elicited at deep body temperatures of 37.45°, 37.8°, and 37.76° in the full term, small for date, and premature infants, respectively. The set-point temperature of sweating tended to be lower with increasing gesta-tional and postnatal age, and with vigorous muscular activity. The physiologic weight loss of about 3%, and the intrauterine growth retardation resulted in significant increase in this threshold temperature. The maximal sweat rate of the premature infants (1.43 W/kg) was significantly lower than that of the full term (1.81 W/kg) and small for date infants (2.32 W/kg): P < 0.05 and 0.01, respectively. Heat loss by radiation and convection was directly related to the mean skin temperature; it was only when the latter reached the value of 37° that radiative plus convective heat loss became positive. There was a close inverse relation between the total heat loss and heat storage. After the beginning of sweating, the heat storage of full term and small for date infants sharply decreased and stabilized around 0, which showed that a new thermal steady state was reached. The premature infant was not able to reach this new equilibrium and the heat storage remained positive. The full term and small for date infants could keep the body temperature at a steady level of 37.66° and 37.98°, respectively, whereas the esophageal temperature of the premature infants kept on increasing. The cutaneous thermal conductance, an indicator of the heat-transferring blood flow, was at first negative, which showed that heat was transferred from the surface to the core. Later, before the evaporative heat loss, it increased and reached the maximal value at a body temperature of 37.6° in the normal, and of 37.9° in both the small for date and premature groups. The metabolic rate for the small for date and premature infants was significantly higher than that for the full term infants, and it directly related to the deep body temperature in each group. In the new thermal equilibrium, the metabolic rate of the full term infants was about 20% lower than that measured under neutral ambient conditions. We suggest that the term “neutral thermal environment” must be reconsidered. Speculation: A new method, gradient layer direct calorimetry, gave us the opportunity to measure directly the different heat losses of the neonate under well controlled experimental conditions, and to compare these data with the results obtained by indirect calorimetry.

The aim of this work was to verify if the presence of trees and its height in formed silvipastoral systems with eucalyptus planted in rank can modify the microclimate and improve the environment for bovine raising during the day in summer. It was evaluated the microclimate of the environment in formed silvipastoral systems in rank of eucalyptus with 8 m, 18 m and 28 meters of height, compared to a system no shade in the summer. The experimental design was a split plot with six hour time in sub parcels. The systems are made up of parcels and the months as block in four replications and the interaction hour × system. The air temperature, black globe temperature, relative humidity and wind speed were observed to create the following indexes for thermal comfort: temperature-humidity index; black globe-humidity index; heat load index and the radiant thermal load. Excepted for the relative humidity, there was interaction for time × system for all variables and indexes. Interaction occurred for: air temperature at 10 a.m. and 6 p.m.; wind speed from 8 a.m. to 4 p.m.; temperature humidity index at 10 a.m. and 12 p.m.; black globe temperature, black globe humidity index, heat load index, and radiant thermal load at all the hours. During the summer, the system with shade of 28 m trees had the lowest average of black globe temperature; wind speed; black globe humidity index; radiant thermal load index; and heat load index. There was a reduction of wind speed average in systems 8 m, 18 m and 28 m trees in, respectively, 20.7; 50.0 and 48.0% in relation to no shade system; however it was not proportional to the height, with influence of the rank porosity and pantries height. Nevertheless, for radiant thermal load index the reduction was proportional to the height of the trees with 10.24; 12.49 and 20.76%, respectively, for 8 m, 18 m and 28 meters of height. There was a reduction of the thermal stress in the environment due to the presence of trees, being the heat load index thermal the index that better demonstrated the effect, despite of not being proportional to the rank height.