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Showing papers by "Ephraim M Sparrow published in 1994"


01 Jan 1994
TL;DR: In this article, passive recovery at room temperature was compared to active cooling by ice packs or convective air for exercise-induced heat stress and its subsequent treatment, and new insights into the occurrence of exercise induced heat stress were gained.
Abstract: IN1RODUCTION Continuous exposure to high environmental temperatures makes an individual physiologically and psychologically prone to heat stress injury. [6] Obviously prevention is preferable to treatment. The key to the prevention and treatment of heat stress is to provide individuals with adequate fluids and a periodic exposure to a cool environment. [2,5] Nevertheless, heat stress does occur and treatment is needed. In the past, the cornerstone of treatment has been to rapidly cool the victim (e.g. using ice packs) and to administer fluids.[6] Unfortunately, ice packs or cold water baths are often impractical and time consuming means to treat heat stress in the field or other emergency situations. The present study was performed to gain new insights into the occurrence of exercise-induced heat stress and its subsequent treatment Le., passive recovery at room temperature was compared to active cooling by ice packs or convective air.

1 citations


01 Jan 1994
TL;DR: In this article, a thermal mannequin was designed to provide highly localized heat flux data at as many as 28 distinct surface locations, and each gauge is a guard-heated, insulated calorimeter.
Abstract: In appraising thermal mannequins that have been designed and fabricated over the last 50 years, two insufficiencies are apparent Most importantly, the existing mannequins produce surface-averaged heat transfer rates over each of their sections [2]. Secondarily, all but two mannequins had no more than 16-19 measurement sites. Data from the two with more sites were usually combined into 16-19 sections for reporting purposes. The mannequin developed here was designed to provide highly localized heat flux data at as many as 28 distinct surface locations. The heat flux gauging system built into the mannequin enables separate identificatiori of the convective and radiative components of the heat flux. Each gauge is a guard-heated, insulated calorimeter. Different surface fmishes of the face ofthe calorimeter facilitate radiation-convection separation. The mannequin is built to accommodate 28 individual gauges. METHODS The essential components of each gauge include a disk-shaped calorimeter, a guard-heating system to prevent extraneous heat losses or gains at the back face of the calorimeter disk, and suitable insulation to minimize heat losses/gains at the lateral faces of the disk. The front face of the calorimeter disk is flush with the surface of the mannequin. Convective and radiative interactions between the calorimeter and its surroundings occur at the front face.

1 citations


01 Jan 1994
TL;DR: In this paper, a multistage cooling system for inducing controlled, mild hypothennia, designated Polar Bair™, has been developed to produce cool convective air which is diffused over a patient by a standard Bair Hugger® blanket.
Abstract: A device for inducing controlled, mild hypothennia, designated Polar Bair™, has been developed to produce cool convective air which is diffused over a patient by a standard Bair Hugger® blanket. Thermoelectric technology is utilized to cool the air. This technology offers several inherent advantages compared with conventional cooling systems such as reliability, quiet operation, and precision temperature control. Furthermore, a thennoelectric cooler can become a heater by merely reversing voltage polarity. One- and three-dimensional mathematical models were developed to quantify the perfonnance characteristics of a three-stage cooling unit. System optimization studies were conducted both numerically and experimentally to assess machine capabilities. METHODS Design methodology for the multistage cooling system included a numerical analysis of the fin arrays which extract heat from the air and those which deliver heat to a sink. The heat exchange system consists of a stacked arrangement of three stages, each composed of a central air-cooling fin array, two flanking heat-sink arrays, and eight thennoelectric heat pump modules, as illustrated in Figure 1. The air-cooling arrays are aligned in series to provide a continuous airflow passage, while the heat-sink arrays are arranged in parallel. Each airflow circuit is provided with its own blower, and the cool side is fitted with a 0.2-micron HEPA air filter. The three air­ cooling arrays are constructed of 1.02-mm thick, 1100 series aluminum fins staked between 7.94-mm-thick aluminum baseplates (surfaces lapped), while each of the six heat-sink arrays, constructed of the same materials, has one baseplate. Four thennoelectric modules (24 total) are installed between each cold and hot baseplate. A 900-W DC power supply developed at Augustine Medical, Inc. is required to power the modules. The respective convective heat flows from the cool-side air and to the heat-sink air are coupled via heat conduction across the thermoelectric modules.

01 Jan 1994
TL;DR: In this paper, the fibexghs exterior of a mannequin is sectioned in order to minimize thermal communication among the eighteen surface zones which were selected for temperature monitoring, and a thermocouple is installed at a representative surface location in each zone in a manner that minimizes measurement errors due to extraneous heat conduction.
Abstract: METHODS The fibexghs exterior of a mannequin is sectioned in order to minimize thermal communication among the eighteen surface zones which were selected for temperature monitoring. A thermocouple is installed at a representative surface location in each zone in a manner that minimizes measurement errors due to extraneous heat conduction [l]. In addition, the junctions are buried 0.16 cm below the surface of the mannequin to avoid measurement errors due to radiation. The leads from the thennocouples traverse the mannequin's interior, exiting through an aperture in its lower back. The leads pass through slits in the underlying mattress and frame and terminate at an automated data acquisition unit. The mannequin's interior is Emspray EM-220 foam (USA). This foam was selected because its low thermal conductivity accentuates the thermal isolation of surface zones and minimizes any depression in temperature at the thermocouple junctions resulting from extraneous heat conduction [ 13. In addition, the foam provides prolonged thermal transients and structural support. Five different waxming systems, designated here as A, B, C, D, and E, are compared. These warming systems are described in Table 1.