Development of the design of a new working section cooled by a dispersed coolant flow for a stand with induction heating

The paper presents a description of the design of a new working section cooled by a dispersed coolant flow for a stand with induction heating. The choice of the material of the working area and the method of spraying has been substantiated. The first commissioning experiments were carried out in a stationary cooling mode, with the parameters of the coolant p = 1.7 · 105 Pa, G = 3.8 · 10-3 kg/s.

Гибридные режимы работы термоэлектрических модулей

It is suggested that thermoelectric coolers designing should not be limited to the extreme modes of their operation. In some cases, it is convenient to use the so called hybrid modes - a combination of the extreme mode of maximum coefficient of performance for large temperature differences and a general cooling mode for small ones. The proposed hybrid mode makes it possible to control the cooling capacity of the module and not to confine this value to that under the extreme operating conditions, the maximum coefficient of performance in particular.

USE OF ANALYSIS TECHNIQUE FOR IMMOBILIZED YEAST SACCHAROMYCES CEREVISIAE IN THE BIOTECHNOLOGICAL INDUSTRY

Article is devoted to the current state and problems of microbial cells immobilization and also prolonged storage of immobilized cells systems for the aims of biotechnological industry. In the experimental part immobilization conditions for the cells S. cerevisiae in alginate gel and vitality test, which had given high reproducibility of experimental results, were developed. Experimental results showed that viability of immobilized cells was higher than that of free yeast cells. It is possible that gel matrix has a protective effect on yeast cells during freezing. Comprehensive effect of cooling modes and preservation protective mediums, which contain sodium alginate, on viability of yeasts has been investigated. Advantage of yeast cells storage in immobilized state was shown experimentally. It was found that cooling mode and composition of preservation medium affect on the viability of S. cerevisiae cells during cryopreservation. In all freezing medium, both without protective components and with addition of a cryoprotective agent, the best results were obtained with cooling at a rate of 1°C/min. Viability indices in the samples were: 73.1 % – in distilled water; 90.8 % – in 1 % sodium alginate solution; 87.1 % – in 5 % DMSO solution and 86.1 % – in 1 % sodium alginate solution with the addition of 5 % DMSO. When cells were frozen in a 5 % DMSO solution and in a 1 % sodium alginate solution with the addition of 5 % DMSO, number of viable cells also decreased as cooling rate increased, but, probably, did not differ from the cell viability index in those samples that were frozen in 1 % sodium alginate solution. The highest results of viability for S. cerevisiae yeast cells were obtained during slow cooling for all cryoprotective mediums. For the first time, high cryoprotective properties of sodium alginate solution, were shown. Obtained results are enable to recommend the sodium alginate as a carrier for cryopreserved immobilized cells when using it in biotechnological processing for biologically active substances production.

On the Use of Wearable Face and Neck Cooling Fans to Improve Occupant Thermal Comfort in Warm Indoor Environments

Face and neck cooling has been found effective in improving thermal comfort during exercise in the heat despite the fact that the surface area of human face and neck regions accounts for only 5.5% of the entire body. Presently very little documented research has been conducted to investigate cooling the face and neck only to improve indoor thermal comfort. In this study, two highly energy efficient wearable face and neck cooling fans were used to improve occupant thermal comfort in two warm indoor conditions (30 and 32 °C). Local skin temperatures and perceptual responses while using the two wearable cooling fans were examined and compared. Results showed that both cooling fans could significantly reduce local skin temperatures at the forehead, face and neck regions by up to 2.1 °C. Local thermal sensation votes at the face and neck were decreased by 0.82–1.21 scale unit at the two studied temperatures. Overall TSVs decreased by 1.03–1.14 and 1.34–1.66 scale units at 30 and 32 °C temperatures, respectively. Both cooling fans could raise the acceptable HVAC temperature setpoint to 32.0 °C, resulting in a 45.7% energy saving over the baseline HVAC setpoint of 24.5 °C. Furthermore, occupants are advised to use the free-control cooling mode when using those two types of wearable cooling fans to improve thermal comfort. Finally, despite some issues on dry eyes and dry lips associated with those wearable cooling fans, it is concluded that those two highly energy-efficient wearable cooling fans could greatly improve thermal comfort and save HVAC energy.

Development of a laboratory nozzle chamber installation for the humidification of buildings

The nozzle chamber, in which water is sprayed into the air stream using mechanical nozzles, is the main unit for these processes in central air conditioning systems (AHUs). The types of nozzles used do not have a sufficiently high effect of interfacial surface forming due to increased metal usage and the broad total dimensions of certain chambers, i.e., they do not have intensive heat and mass transfer. The authors performed testing of the apparatus in the direct iso-enthalpic air cooling mode to improve the performance of the nozzle chamber. Thus, the experiments conducted confirm the relatively high efficiency of FET operation at small values of irrigation coefficient B ≥ 1.0. The area highlighted is characterised by the unstable operation of other nozzle types. Therefore, FET nozzles can be operated at irrigation factor values B = 0.1…1.0. Experiments have shown that this equation is applicable for practical calculations, with a relative error of ±6.7%. The aerodynamic resistance of the spray chamber nozzle chambers is also according to the data not exceeding 160 Pa.

Effect of a Geothermal Heat Pump in Cooling Mode on the Housing Environment and Swine Productivity Traits

This study compared the effects of the cooling mode of a geothermal heat pump (GHP) system with those of a traditional cooling system (ventilation fans) inside a pig house on the internal house temperature, harmful gas emissions, and the growth performance of the pigs. During the 19-week experimental period, the temperature inside the house connected to the GHP cooling system was significantly lower (p < 0.05) than that of a house with a conventional cooling system. Similarly, the temperature–humidity index (THI) was significantly reduced (p < 0.05) in the GHP cooling system-connected pig house. Furthermore, the concentrations of ammonia (NH3) and hydrogen sulfide (H2S) were also decreased significantly in the GHP-installed pig house (p < 0.05). However, no differences were observed in the concentrations of particulate matter (PM2.5) and formaldehyde (p > 0.05). The pigs reared in the GHP-equipped pig house gained significantly more weight (p < 0.05) by the end of the experiment. The GHP cooling system can therefore be implemented as a renewable, environmentally friendly energy source in pig farms for sustainable swine production without adversely affecting the productivity parameters.

A Precursory Signal of the Central Pacific El Niño Event: Eastern Pacific Cooling Mode

In recent decades, the tropical Pacific frequently experiences a new type of El Niño with warming center in the central tropical Pacific (i.e., the CP-El Niño) with distinct global climate effect to the traditional El Niño (i.e., EP-El Niño). Predicting the El Niño diversity is still a huge challenge for climatologists partly due to the precursory signals of El Niño events with different type is unclear. In the present study, a novel precursory signal that presents a negative sea surface temperature anomaly in the eastern tropical Pacific (i.e., EP-cooling mode) is revealed, which tends to evolve into a CP-El Niño event. The transition from the EP-cooling mode to CP-El Niño is explained by the basin-scale air-sea coupling in the tropical Pacific and teleconnections between the tropical and North Pacific. With the EP-cooling mode as a predictor, the forecast skill for the CP-El Niño in hindcast experiments is obviously improved by using regression models. The results in the present study are therefore instructive for promoting a better understanding of El Niño diversity and predictability.

Experimental investigation on the impact of evaporative cooling based battery thermal management system on charging process of valve regulated lead acid batteries in E-bike

The thermal behaviour of valve regulated lead acid batteries with an evaporative cooling-based thermal management system is experimentally examined during the charging process of an E-bike. The thermal behaviour of valve regulated lead acid batteries is investigated during charging process with three different cooling strategies: evaporative cooling-based battery thermal management system, pre-cooling + battery thermal management system, and natural convection. The valve regulated lead acid batteries from the OREVA ALISH E-bike were used for testing. A portable evaporative cooling system was built for investigation based on available space on the E-bike. The results show that the developed evaporative cooling-based battery thermal management system kept temperatures between 1.5°C and 2.2°C below ambient during the charging process. The temperature of the battery during the charging process is increased slightly, by 1.6°C during the pre-cooling + battery thermal management system cooling mode. The temperature uniformity among valve regulated lead acid batteries was improved during the charging process with pre-cooling + thermal management system cooling mode.