An Investigation of Thermoelectric Generators Used as Energy Harvesters in a Water Consumption Meter Application

In this study, we present the results of measuring the performance of selected Peltier cells such as thermoelectric Peltier cooler modules (TEC), thermoelectric micro-Peltier cooler modules (TES), and thermoelectric Seebeck generator modules (TEG). The achieved results are presented in the form of graphs of powering system output voltage or power efficiency functions of the load impedance. Moreover, a technical solution is also presented that consists of designing a water consumption power supply system, using a renewable energy source in the form of a Peltier cell. The developed measuring system does not require additional batteries or an external power source. The energy needed to power the system was obtained from the temperature difference between two sides of a thermoelectric cell, caused by the measured medium which was flowing in a copper water pipe. All achieved results were investigated for the temperature difference from 1 to 10 K in relation to the ambient temperature.

INFLUENCE OF THE CURRENT PULSE SHAPE ON THE DYNAMICS OF THE TEMPERATURE FIELD OF THE THERMOELECTRIC COOLER BRANCH

Numerical simulation of thermoelectric processes in a branch of a solid–state thermoelectric Peltier cooler in a non–stationary mode is performed. Some examples show the effect of changes in the amplitude of the current pulse over time on the temperature in the branch of the thermoelectric element.

Ice Formation due to Condensation of Moist Air on Commercial Wicks

Heat pipes are valuable heat transfer devices that can be used in space; however, when exposed to the extremely low temperature of space, the working fluid can freeze. Currently, there are different methods to help mitigate freezing effects, including non-condensable gas-charged heat pipes and understanding ice formation on surfaces (e.g., typically surfaces with hydrophobic coatings). However, there is limited research about ice formation on wicks. Different wicking structures may delay freezing or mitigate freezing effects. This paper will investigate ice formation on two surfaces — commercial sintered and grooved wicks. An indoor environmental chamber was used to control ambient air temperature (i.e., 22°C) and relative humidity (i.e., 60% RH) and a Peltier cooler was used to control the surface temperature (i.e., −5°C). The resulting condensation of water onto the surface and then freezing was recorded for an hour and analyzed for the time freezing began on the surface (i.e., ice is initially visible) and the time freezing was complete on the surface. Initial results indicate that the sintered wick begins to freeze first (on average at 10.73 minutes versus 13.66 for the grooved wick) and the freezing front propagates faster (taking on average 10.83 minutes versus 12.44 minutes for the grooved wick). From the analysis, it is seen that the wicking surface structure influences the initial freezing time and the rate the freezing front propagates across the surface. These differences and the causes are investigated in this paper. These differences can, in the future, be exploited to design an optimal freeze-tolerant heat pipe and heat pipe freezing models.

Using Optical Activation to Create Hydrogen and Hydrogen-Containing Gas Sensors

It was found that at room temperature the value of the photoinduced current of Schottky diodes based on heterostructures InP/GaInAs/Pd at a hydrogen concentration of 0.03% is reduced by two orders of magnitude compared to the value without hydrogen. The value of the photoinduced current depends on the thickness of the depleted region on the surface of the semiconductor. A small change in the charged layer of H+ can cause a significant change in the thickness of this region and as a result, a strong change in the photoinduced current. This effect on current is much stronger than the influence of hydrogen concentration or capacitance without optical activation. As a result, it becomes possible to create hydrogen and hydrogen-containing gas sensors with much better sensitivity at room temperature. The original design of a miniature H2 sensor including an IR LED, a Schottky diode with a Pd contact, a Peltier cooler and a thermosensor is demonstrated.

1198 Efficacy of Direct Thermoelectric Forehead Cooling for Treating Insomnia Symptoms

Introduction Prior studies have shown beneficial effects of forehead cooling in insomnia patients using a device that circulates cooled fluids through a forehead pad. The current study aimed to determine if a device that cooled via direct thermoelectric contact to the forehead via a Peltier cooler would have similar effects in individuals with insomnia symptoms. Such a technology may allow for form factors that may have advantages for some individuals. Methods An intelligent, portable and battery-operated forehead cooling system using thermoelectric coolers (TECs) with a user selectable temperature range between 14C and 18C was used in the study. Individuals with insomnia symptoms (N=30, 25 female) were recruited and studied at 2 geographic locations. Each participant received pre- and post- treatment insomnia severity as well as daily sleep diary assessments over 1 week of baseline and 4 weeks of treatment. Results Participants’ insomnia symptoms improved over baseline in insomnia severity index (M + SD = 19.7 + 3.8 pre- vs 9.4 + 5.3 post-treatment, t = -9.3, p<0.00001), in sleep latency (M + SD = 43.0 + 40.8 minutes pre- vs 20.7 + 22.7 minutes post-treatment, t = 6.8, p<0.00001), in minutes awake after sleep onset (M + SD =63.0 + 59.2 minutes pre- vs 24.5 +34.5 minutes post-treatment, t = 8.0, p<0.00001) and in sleep quality (0-10 scale with 10 = best, M + SD = 4.1 + 1.9 pre- vs 6.8 + 2.2 post-treatment, t = -13.4, p<0.00001). Conclusion Forehead cooling via direct thermoelectric contact to the forehead via a Peltier cooler had beneficial effects on subjective insomnia symptoms. These promising preliminary data suggest the need for further large scale randomized controlled trials to establish the efficacy of forehead-cooling using direct thermoelectric contact to the forehead via a Peltier cooler on insomnia symptoms. Support Ebb Therapeutics, Pittsburgh, PA 15222

Design of Portable Conditioning Chamber with Peltier Element for Transfusion Blood Temperature

A research has been conducted on the design of conditioning chambers with Peltier elements aimed at controlling transfusion blood temperature and analyzing the control system that has been made. The working principle of the control system that is made is the temperature sensor will read the temperature in the chamber, if the temperature reads above 10 °C, the relay will light up and electricity will flow so that the Peltier cooler will work, if the temperature has reached 10 °C, then the relay will off and the electricity will stop to save energy. The relay will turn on again if the temperature rises above 10 °C. The results obtained from this experiment is the Peltier element can cool down for 30 minutes with variations in load 0 mL, 350 mL, 700 mL, 1050 mL, and 1400 mL in the temperature range of 2 °C to 10 °C.

MODELING THE EFFECT OF HEAT EXCHANGE ON THE EFFICIENCY OF A THERMOELECTRIC COOLER

Numerical modelling thermal and thermoelectric processes in a branch of solid–state thermoelectric of Peltier cooler is performed, taking into account heat exchange by convection and radiation. The numerical calculation of the branch was carried out in the mode of the maximum temperature difference.

Peltier Cooling for Low Concentration Photovoltaic Cells: Numerical Modeling and Feasibility Study

Thermal management of concentrating photovoltaic (CPV) panels is known as a major concern that has been investigated in the recent years. Appropriate cooling techniques must be employed to maintain optimum cell temperature, thus improving system efficiency and life cycle. Thermoelectric cooling offers several attractive characteristics including high controllability, no need to refrigerant, modularity, quiet operation and more. In this paper, the possibility of using convective cooling using a water channel along with thermoelectric cooling for a low concentration photovoltaic (LCPV) module is investigated. A numerical model is developed using COMSOL Multiphysics® and MATLAB® to assess the performance of a novel CPV-TE system. The proposed system consists of a Thermoelectric cooling (TEC) module attached to the backside of a photovoltaic (PV) cell. A water channel has been implemented on the backside of the Peltier module to provide effective heat removal using water flow. A parametric study is conducted on the proposed system by varying solar concentration incident on the PV, input current to the Peltier cooler and inlet velocity and temperature of the water flow. The temperature distribution through the system, power output from the PV module and energy consumption by the Peltier module are determined under different operational circumstances. The results are extensively discussed to provide an understanding regarding the feasibility of the proposed system.

Electrochemical Redox Refrigeration

The high conformational entropy change of the Fe(CN)63−/4− redox reaction can be used as the basis for a compact electrochemical refrigerator. This device is comparable to a liquid version of a Peltier cooler, with two distinct advantages: (1) the entropy change per carrier (1.5 mV/K) of the electrochemical refrigerant is more than 5 times larger than that of state-of-the-art solid thermoelectric materials; and (2) the liquid electrolyte can be advected continuously away from the cooling junction, so that Joule heating in the bulk element does not diminish the delivered cooling effect. In this work, we use infrared microscopy to visualize the thermal aspects of Fe(CN)63−/4− redox, and compare the estimated cooling to calculated values with and without electrolyte flow. While the temperature differences achieved in a single cell are small (~50 mK) and not enhanced by electrolyte flow, the cooling power density (~0.5 W/cm3) is high when normalized to the small electrode volume. Non-dimensional figures of merit are proposed to identify electrochemical redox species for maximizing the cooling effect.