Improving the maneuverability and thermal efficiency of modern cogeneration systems based on gas turbine power plants

The paper is devoted to the issue of increasing the maneuverability and efficiency of modern cogeneration systems based on gas turbine power plants. Promising solutions for increasing the maneuverability of GTU-CHPP by using heat accumulators and the formation of a preheating circuit of the network water are considered. It is shown that in the non-heating period, it is possible to increase both the thermal efficiency and the generated electric power by installing a heat exchanger in front of the compressor. The calculation results show that this provides an increase of 0.4% in the net electrical efficiency by and an increase 3.3% in the annual electricity generation.

Design and feasibility verification of regenerative system of electric thermal storage boiler for peak shaving in summer in power plant

During the heating period, the thermal storage electric boiler helps the thermal power units to participate in the deep peak regulation by converting the electric energy into heat energy for heating users, but in the non-heating period, the thermal storage electric boiler can not operate because there is no heat user, as a result, the thermal storage electric boiler is shut down in summer, and can not assist the thermal power unit to participate in the deep peak regulation. Therefore, this paper designs an electric thermal storage boiler regenerative system for peak shaving in summer. In this regenerative system, electric boiler is used to heat circulating water in heating period, and electric boiler is used to heat condensed water in non-heating period, and in the non-heating period, the number of low-pressure heaters can be adjusted according to the load and heat storage capacity of the units, so that the electric boiler can assist the thermal power units to participate in the deep peak regulation throughout the year, taking a 350MW unit with 70MW regenerative electric boiler as an example, the heat exchange capacity is calculated to verify the feasibility of the regenerative system. In this paper, a new method of heating condensate by regenerative electric boiler in non-heating period is proposed to solve the problem that the new energy can not be used and the energy is wasted in summer.

The community heating network’s thermal condition assessment

Heat losses at the heating network’s distribution pipelines were identified for Karkivcommunity. Heat losses’ calculation is performed in view of the underground pipelines’ installationin non-accessible ducts. The heating system water temperature is accepted in line with the heatingnetwork temperature chart and according to the design outdoor temperature value for heatingpurposes. Specific heat losses in the network section’ pipelines are accepted at the level of standardvalues for the specified network laying method. The water flow rate at the heat pipeline sections isdefined as per the design heat loads from the buildings connected to the heat supply network. Theheat pipeline segment with uniform diameter is accepted as the rated section. The soil temperatureat the heat pipeline axis laying depth is accepted as 5°C. The heat losses at the structural networkelements are considered by 1.15 coefficient. The calculations are performed in view of the heatingsystem water flow rate and temperate changes along the heat pipeline length. While analyzing thethermal condition of the return pipelines of the community heating network, the changes in the heatcontent of the heating system water flow in the main direction pipeline during mixing with the waterflow from the branches of the main direction line are taken into account. Considering the averagetemperature of the coldest five days consecutively, the total energy loss in heating pipeline for a groupof buildings in Kharkov region are equivalent to 180.8kW.In view of the ambient air temperature changing over the heating period for Kharkiv cityclimate conditions and the current schedule for quality heat energy supply to the consumers controlthe annual heat losses in the community heating network pipelines were calculated. The soil temperature change at the heat pipeline installation depth during the heating period was notconsidered.Heat losses in the microdistrict network for the year are 2184 GJ. The data obtained can beused to compare options when developing a strategy for reforming the microdistrict heat supplysystem.

SELECTING THE HEAT-REFLECTING SCREEN WHILE THE FORMATION OF CONDENSATE IS AVOIDED

This article deals with the problem of choosing the thickness of the heat-refl ecting screen behind the heating radiator, in which the conditions for the formation of condensate on the wall are not achieved. Based on the analysis of the results obtained, the maximum thickness of the screen is established, using the example of penofol, at the calculated temperature diff erence in the conditions of a cold fi ve-day period, and the heat losses and the economic eff ect of this energy-saving measure are determined already during the heating period. Calculations were carried out for a wall made of reinforced concrete, covered with plaster on the outside. This technique can be used for other cases of enclosing structures and various materials of the heat-refl ecting screen.

Determination of the Temperature Graph of Heat Supply With Minimal Heat Losses

Heat losses by pipelines of heat supply systems are calculated for the average temperature of the heat carrier per year or for the heating period for the conditions of a qualitative method of regulating the heat load. The presence of cuts of the temperature graph, the use of other methods of central regulation, are not reflected in the regulatory documents and require special research, which determines the relevance of the work. Heat losses through thermal insulation structures of pipelines have been determined for various graphs of central regulation. Heat losses were determined for each external temperature, taking into account its duration. It is shown that the average linear annual heat losses for most of the graphs correspond to a lower external temperature than the average external temperature for the heating period. Therefore, the calculation must be performed for a higher temperature of the heat carrier than is accepted according to regulatory documents.

The Influence of Environment Factors on Chronic Non-Communicable Diseases in a Heavy Industry City—A Case of Xigu District of Lanzhou City

Taking Xigu District of Lanzhou City as an example, this paper systematically analyzes the spatio-temporal distribution characteristics of patients with chronic non-communicable diseases (NCD) and compares the differences between heating period and non-heating period. Furthermore, the impact paths of natural environmental factors and built-up environmental factors on NCD are probed with the help of the geographic detector. The results are as follows: In time, the incidence of NCD in Xigu district fluctuated from 2012 to 2019. In space, there was an overall declining trend in high incidence rate from the central area to the surrounding areas, among which Xigucheng street was the high-risk area. The incidence of NCD in heating period was higher than that of in non-heating period, and the number of H-H cluster areas was witnessed an obviously increasing growth in Sijiqing Street. There are significant differences in the explanatory power of different factors (if any) for NCD. The explanatory power of each index in Xigu District is as follows: Facility > SO2 > NO2 > PM2.5 > food > Beverage Service > Green Facilities > Traffic Regulations > medical facilities. The interaction between plant facilities and SO2 has the strongest effect on NCD. Except for the negative correlation between greening and medical facilities and the incidence of NCD, all the influencing factors were positively correlated with NCD.

Formation mechanism of β’’-Mg5Si6 and its PFZ in an Al-Mg-Si-Mn alloy: experiment and first-principles calculations

Formation mechanism of β’’-Mg5Si6 and its PFZ in an Al-Mg-Si-Mn alloy was studied by the means of experiment and first-principles calculations. Results show that at 270°C during the 100 °C/h heating period, β’’-Mg5Si6 precipitated inside the dendrites, whereas precipitation free zones (PFZs) of β’’-Mg5Si6 presented near the dendrite arm regions. The formation of the β’’-Mg5Si6 and its PFZ were related to the concentration of vacancy. Low-concertation zones of vacancy formed near the eutectics during the solidification due to the constitutional supercooling, no β’’-Mg5Si6 precipitated in the low-concertation zones of vacancy due to the vacancy-dependence of β’’-Mg5Si6, the Si vacancy-containing β’’-Mg5Si6 was extremely unstable and Si vacancies prefer to stay away from distribution.

Experimental Studies of Moisture Transport in Grain Material and Individual Grain

The issue of moisture transfer in the total mass of the material and in a single grain is discussed taking into account the biological characteristics of the endosperm cells of the grain. Experimental studies of this process have been performed. The results of the oscillating mode with laying have been analyzed. It was found that during the time of laying, the moisture content of the grain shell increases significantly and the moisture content of the core decreases slightly, and during the implementation of the laying after the heating period, a larger amount of moisture moves from the core into the shell than after the cooling period.

TEST OF A PILOT INSTALLATION OF A SOIL REGENERATOR FOR GREENHOUSES

The relevance of the development of ground regenerative heat exchangers is determined by the need to save energy resources for heating greenhouses at night and maintaining the required temperature level during the day. The aim of the work is to study working capacity of a ground regenerator for a greenhouse when testing a pilot plant in full-scale conditions. To achieve this goal the following main tasks were solved: experimental research of soil regenerator pilot plant operation was carried out, the heating period of nozzle and cooling period were determined by the obtained temperature curves, the coefficient of intercomponent heat exchange during the heating period was estimated, the rationality of material choice for granulated nozzle was proved, recommendations on improvement of soil regenerator design for industrial use were developed. The research was conducted on a pilot installation of a soil regenerator, which consists of a heat-exchange duct filled with granulated material and covered with a layer of insulation, and ducts with an exhaust duct fan installed at the outlet. Data on air and nozzle temperatures, which were taken during the day, were used to conduct thermal calculations and assess the efficiency of the ground regenerator. It was determined that the heating period at the selected loading mass of 15.5 kg is not long relative to the duration of the experiment and was 166 min. To increase the amount of accumulated heat it is recommended to increase the weight of the nozzle and air flow rate. It was determined that the coefficient of inter-component heat transfer during the heating period varied between 4 W/m2K and 9 W/m2K. In this case, the Bio number is in the range of 0.05 - 0.10, which allows us to conclude that the use of crushed stone as a nozzle material is rational. It is recommended to increase the thickness of insulation to 4.3 cm so that the heat loss from the heat exchange section does not exceed 5%, and to provide the installation of insulated plugs at the ends of the heat exchange section, closing after the end of the heating period.

Proximal heat stress up-regulates angiopoietin-1 in fingers and reduces the severity of Raynaud’s phenomenon in systemic sclerosis: a single-centre pilot study

ABSTRACT Objectives Raynaud’s phenomenon (RP) is a peripheral vascular disorder that frequently occurs in systemic sclerosis (SSc). Although therapeutic heating seems reasonable given that RP is elicited by cold stimuli, the effects of heating are still unclear. We examined the effects of heating applied on various body parts in SSc patients with RP of fingers. Methods Fourteen SSc patients heated their neck, elbows, and wrists with disposable heating pads for 1 week each. The visual analogue scale (VAS) for RP during each heating period was compared with that of each 1-week pre-treatment interval. On the day after the expiration of each heating period, their finger temperature, the finger blood flow, and angiogenesis-related factors (vascular endothelial growth factor, endostatin, angiopoietin-1, and angiopoietin-2) obtained from the cubital vein and fingertip were measured. Results The mean VAS was significantly reduced during the heating of the neck and elbows. Fingertip blood samples showed significantly increased angiopoietin-1 after each of the heating periods and increased endostatin after wrist heating. After the termination of heating, changes in finger temperature or blood flow could not be detected. Conclusions Heating the neck or elbows can alleviate RP in SSc. The heat up-regulates angiopoietin-1 in the fingers.