COMPARISON OF OPTIONS FOR THE HEAT DISTRIBUTION NETWORK OF THE RESIDENTIAL NEIGHBORHOOD

2021 ◽  
pp. 17-25
Author(s):  
O. Aleksakhin ◽  
S. Yena ◽  
O. Hordiienko ◽  
V. Novikov ◽  
D. Tsemokh
Keyword(s):  
Flow Rate ◽  
Distribution Network ◽  
Water Flow Rate ◽  
Heating System ◽  
Heat Losses ◽  
Rate Variation ◽  
Outdoor Air ◽  
Heat Network ◽  
Residential Neighborhood ◽  
Medium Flow

The comparison of heat losses by pipelines of an extensive residential neighborhood heating system for two options of the distribution network was carried out for a residential neighborhood in Kharkov. The proposed configuration of the heating network differs from the existing ("basic") one in using of the law of heating medium flow rate variation along the heat pipe length. This law takes into account increased flow rate of heating water through branches at the initial sections of the pipeline. The actual flow rate distribution is approximated by a step function. The difference in the laws of flow rate variation is taken into account by the exponent value. The calculation of heat losses was carried out for underground pipelining in non-accessible tunnels. The temperature of heat line water is taken to be the corresponding to the design outdoor air temperature for heating according to the temperature schedule of the heating network. Specific heat losses by pipelines in heat network sections are considered to be at the standard level for non-accessible tunnels. The soil temperature at the depth of the heat pipe axis is taken equal to 5°C. Heat losses by the structural elements of the heat network are taken into account by a factor of 1.15. The variation of the flow rate and temperature of network water in rated pipeline sections is considered in the analysis.  The water flow rate at the sections was found based on the design thermal loads of connected buildings. It is shown that when choosing the configuration of the distribution network of the heating system of a group of buildings, preference should be given to the option with a lower value of the exponent in the equation for heating medium flow rate variation along the length of the main line of the network. For extensive heating networks, this can be achieved by connecting as many buildings as possible to the heating network sections close to a heat supply station. An increase in the network water flow rate through the branches at the initial sections of the pipeline ensures a decrease in heat losses by the network pipelines. For the considered part of a residential neighborhood, the decrease in heat loss at the design outdoor air temperature for heating is 5.5 %.

scholarly journals The community heating network’s thermal condition assessment

2021 ◽  
pp. 136-142
Author(s):  
Alexander Aleksakhin ◽  
Iryna Dubynskaya ◽  
Ilona Solyanyk ◽  
Zhanna Dombrovs’ka
Keyword(s):  
Water Flow ◽  
Flow Rate ◽  
Water Flow Rate ◽  
Heating System ◽  
Ambient Air ◽  
Heat Losses ◽  
Main Direction ◽  
Heating Period ◽  
Uniform Diameter ◽  
System Water

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.

A Distributed Predictive Control of Energy Resources in Radiant Floor Buildings

2019 ◽  
Vol 141 (10) ◽  
Author(s):  
Soroush Rastegarpour ◽  
Luca Ferrarini ◽  
Foivos Palaiogiannis
Keyword(s):  
Energy Storage ◽  
Model Predictive Control ◽  
Water Flow ◽  
Predictive Control ◽  
Flow Rate ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Water Flow Rate ◽  
Heating System ◽  
Energy Resources

This paper studies the impact of using different types of energy storages integrated with a heat pump for energy efficiency in radiant-floor buildings. In particular, the performance of the building energy resources management system is improved through the application of distributed model predictive control (DMPC) to better anticipate the effects of disturbances and real-time pricing together with following the modular structure of the system under control. To this end, the load side and heating system are decoupled through a three-element mixing valve, which enforces a fixed water flow rate in the building pipelines. Hence, the building temperature control is executed by a linear model predictive control, which in turn is able to exchange the building information with the heating system controller. On the contrary, there is a variable action of the mixing valve, which enforces a variable circulated water flow rate within the tank. In this case, the optimization problem is more complex than in literature due to the variable circulation water flow rate within the tank layers, which gives rise to a nonlinear model. Therefore, an adaptive linear model predictive control is designed for the heating system to deal with the system nonlinearity trough a successive linearization method around the current operating point. A battery is also installed as a further storage, in addition to the thermal energy storage, in order to have the option between the charging and discharging of both storages based on the electricity price tariff and the building and thermal energy storage inertia. A qualitative comparative analysis has been also carried out with a rule-based heuristic logic and a centralized model predictive control (CMPC) algorithm. Finally, the proposed control algorithm has been experimentally validated in a well-equipped smart grid research laboratory belonging to the ERIGrid Research Infrastructure, funded by European Union's Horizon 2020 Research and Innovation Programme.

Air temperature prediction model to control solar energy heating in a germination greenhouse at night

1998 ◽  
Vol 38 (4) ◽  
pp. 409 ◽  
Author(s):  
Ibrahim E. A. Elbatawi
Keyword(s):  
Solar System ◽  
Solar Energy ◽  
Air Temperature ◽  
Flow Rate ◽  
Water Flow Rate ◽  
Weather Forecast ◽  
Hot Water ◽  
Outdoor Air ◽  
Maximum Temperatures ◽  
Air Temperature Prediction

Summary. The outdoor air temperature is not constant especially in spring in Okayama city. The average night temperature ranges from –2 to 20°C which is too low for the germination of most seeds. A good knowledge of the future outdoor air temperature is necessary to decide if greenhouse heating is needed for the next day. Using measured temperatures from the preceding days and considering the minimum and maximum temperatures given by the weather forecast, it was possible to accurately compute the temperature for the next day. Pumpkin, eggplant and tomato seeds were used in this study. A solar system was used to heat the air inside a greenhouse at night using an air–water–air heat exchanger and make a comparison with an unheated greenhouse. The performance of the solar collector and methods of heat exchange were tested. It was shown that the solar energy collected was sufficient for warming a nursery greenhouse overnight. The system operated with a hot water flow rate of 0.647 L/min and an air flow rate of 9.21 m3/min and could maintain the greenhouse temperature between 16 and 20°C. The quantity of heat collected and delivered by the solar system from incident solar radiation was about 50% in a day. Heating the air inside the greenhouse at night produced 100% germination for all seedlings. In comparison, in the unheated greenhouse the germination ratio was 100, 93 and 27% for pumpkin, eggplant and tomato respectively. The germination ratio outside the greenhouses was 100% for pumpkin, 67% for eggplant and zero for tomato.

scholarly journals A Non-Intrusive Signal-Based Fault Diagnosis Method for Proton Exchange Membrane Water Electrolyzer Using Empirical Mode Decomposition

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4458
Author(s):  
Farid Aubras ◽  
Cedric Damour ◽  
Michel Benne ◽  
Sebastien Boulevard ◽  
Miloud Bessafi ◽  
...  
Keyword(s):  
Fault Diagnosis ◽  
Empirical Mode Decomposition ◽  
Flow Rate ◽  
Proton Exchange Membrane ◽  
Water Flow Rate ◽  
Proton Exchange ◽  
Rate Variation ◽  
Mode Decomposition ◽  
Exchange Membrane ◽  
The Impact

This work focuses on a signal-based diagnosis approach dedicated to proton exchange membrane water electrolyzer (PEM WE) anode pump fault. The PEM WE cell measurements are performed with an experimental test bench to highlight the impact of water flow rate in the anode compartment. This approach is non-intrusive, and it can detect anode flow rate variation during the electrolysis and is designed to fulfill online diagnosis requirements. Contrary to electrochemical impedance spectroscopy-based approaches (EIS), this method stands out from existing procedures as a result of its few requirements, excluding any signal with perturbing amplitude. Therefore, the electrolyzer remains continuously available, even while the analysis is performed. The empirical mode decomposition (EMD) is used to decompose the signal variation into a sum of amplitude modulation and frequency modulation (AM-FM) components, called intrinsic mode functions (IMFs). In this work, the PEM WE current signal is decomposed into several IMFs using EMD. Then, the energetic contribution of each IMF is calculated. Experimental results exhibited that the energetic contribution of IMFs can be used as relevant criteria for fault diagnosis in PEM WE systems. This process only requires monitoring of the PEM WE current and has a low computational cost, which is a significant economic and technical advantage.

scholarly journals EFFECT OF FLOW STEERING ANGLE TOWARD THE HYDROKINETIC TURBINE PERFORMANCE

2019 ◽  
Vol 3 ◽  
pp. 20-31
Author(s):  
Rudy Soenoko ◽  
Hastono Wijaya
Keyword(s):  
Kinetic Energy ◽  
Water Flow ◽  
Flow Rate ◽  
Turbine Blades ◽  
Water Flow Rate ◽  
Rate Variation ◽  
Steering Angle ◽  
Turbine Performance ◽  
Hydrokinetic Turbine ◽  
Turbine Runner

The kinetic turbine is one of the solutions for use in low-speed river flows ranging from 0.01–2.8 m/s. This kinetic turbine is used as a conversion equipment to convert the water kinetic energy into an electrical energy. The working principle of a kinetic turbine is utilizing and relies on the water kinetic energy. Water flowing into the turbine area will produce a momentum on the turbine blades. This momentum change would then push the turbine blades and finally spin the turbine runner. The aim of research is thedetermination of the effect of water flow steering angle (a) and water flow rate variation in the kinetic turbine performance. This research uses vertical axis kinetic turbines with eight curve blade attached to the turbine runner. The variables used are two values of water flow steering angle, namely 25°and 35°. The water flow rate variation of 30 m3/h, 35 m3/h, 40 m3/h and 45 m3/h. The method used in this study uses a real experimental method. These two variations would then compare with the result of a hydrokinetic turbine performance done on the previous research. The results show that the water flow steering angle a affected the kinetic turbine performance (power, efficiency and torque). From these several water flow steering angle and water flow rate variations, the turbine performance with a 35° water flow steering angle get the highest performance compared with the use of 25° and 14° water flow steering angle. The greater the flow angle and the greater the water flow rate, the greater the torque, power and efficiency. The highest turbine power produced, P=17.5 W, occurs on the 35° water steering angle, and on a Q=45 m3/h water flow rate and on a 80 rpm turbine rotation. While the highest turbine efficiency, h=27 %, occurred on the Q=30 m3/h water flow rate, on a 60 rpm turbine rotation and on a water flow steering angle a=35°. The highest turbine torque, 3.1 Nm, occurs at Q=45 m3/h water flow rate at a maximum turbine braking and on a water steering angle a=35°.

Investigation on the Mechanism of Energy Saving and Efficiency Enhancement for Fluid Ejector

2011 ◽  
Vol 121-126 ◽  
pp. 2804-2808
Author(s):  
Gui Ju Xing ◽  
Zi Huan Li ◽  
Hong Liang Zheng ◽  
Jian Wang ◽  
Fu Sheng Jiang
Keyword(s):  
Theoretical Analysis ◽  
Energy Saving ◽  
Flow Rate ◽  
Water Flow Rate ◽  
Turbulent Energy ◽  
Energy Dissipation Rate ◽  
Rate Variation ◽  
Efficiency Enhancement ◽  
Pumping Power ◽  
Rate Condition

Experiments were implemented on a prototype commercial liquid ejector to measure its hydraulic efficiency and the change of which along with a certain range of water flow rate variation was also recorded. Based on theoretical analysis and numerical simulation methods, we improved the ejector’s structure by modifying the suction part of it. Four ameliorated ejector structures, with increased pumping power and reduced flow resistance compared to the prototype, are proposed. Under the same working flow rate condition, flow field computations were conducted on the prototype and the four improved structures. The computational results show that the pumping power increases by 75.97%, the drag coefficient reduces 0.0908, the maximum turbulent energy dissipation rate decreases by 38.88% and the absolute value of the efficiency increases by 13.66%. The work validates the correctness of the theoretical analysis about the mechanism of energy-saving and efficiency enhancement for fluid ejector, and provides a more effective method to improve the performance of liquid ejector.

Performance of Hybrid Photovoltaic and Thermal (PV/T) Collector With and Without Electricity Generation

2009 ◽  
Author(s):  
Erkata Yandri ◽  
Naokatsu Miura ◽  
Sadsuke Ito ◽  
Toru Fujisawa ◽  
Mika Yoshinaga
Keyword(s):  
Steady State ◽  
Flow Rate ◽  
Thermal Performance ◽  
Thermal Energy ◽  
Thermal Efficiency ◽  
Electricity Generation ◽  
Water Flow Rate ◽  
Photovoltaic Cells ◽  
Heat Losses ◽  
Wind Environment

This paper presents the experimental results that involve the analysis of a photovoltaic and thermal (PV/T) hybrid collector, which has an integration of the photovoltaic cells and a solar thermal panel into one collector, by focusing on its thermal efficiency when both thermal and electrical energies are generated and when only thermal energy is generated. The experiment was performed at 4 different collector input temperatures, i.e., 12°C, 15°C, 20°C, and 25°C under the condition that the water flow rate was 4 l/min. We analyzed during the period of peak irradiation from 12:00 to 13:00 to obtain the semi-steady-state thermal performance. Besides, in order to remove the differences of the wind environment, the wind heat losses are calculated in the analysis. The result shows that the thermal efficiency of the PV/T collector decreases slightly when only thermal energy is generated as compared to that when both thermal and electrical energies are generated.

scholarly journals RESISTÊNCIA DE DIFERENTES TIPOS DE TUBOGOTEJADORES AO ENTUPIMENTO POR PRECIPITAÇÃO QUÍMICA DE CÁLCIO

Irriga ◽  
2004 ◽  
Vol 9 (2) ◽  
pp. 115-125 ◽  
Author(s):  
Nildo Da Silva Dias ◽  
Marcus Vinicius A. M. de Oliveira ◽  
Rubens Duarte Coelho
Keyword(s):  
Standard Deviation ◽  
Flow Rate ◽  
Calcium Sulfate ◽  
Operation Time ◽  
Chemical Precipitation ◽  
Drip Line ◽  
Rate Variation ◽  
Trickle Irrigation ◽  
Flow Reduction ◽  
Medium Flow

RESISTÊNCIA DE DIFERENTES TIPOS DE TUBOGOTEJADORES AO ENTUPIMENTO POR PRECIPITAÇÃO QUÍMICA DE CÁLCIO   Nildo da Silva Dias1; Marcus Vinicius A. M. de Oliveira2; Rubens Duarte Coelho11Departamento de Engenharia Rural, Escola Superior de Agricultura Luiz de Queiroz, Universidade de São Paulo, Piracicaba, SP,  [email protected] de Recursos Naturais, Faculdade de Ciências Agronômicas, Universidade Estadual Paulista, Botucatu, SP    1 RESUMO  Com o objetivo de avaliar a susceptibilidade de tubogotejadores ao entupimento por precipitados químicos à base de sulfato de cálcio, foi desenvolvido um experimento no Laboratório de Irrigação da Escola Superior de Agricultura “Luiz de Queiroz”. Foram utilizados três tipos de tubogotejadores não autocompensáveis (Carbo Drip 2,30 L h-1 – T1; Hydro Gol, 2,00 L h-1 – T2 e Typhoon 1,70 L h-1 – T3) instalados em uma bancada, com 6 m de comprimento x 1,3 m de largura e 1,45 de altura, com cinco segmentos de linhas para cada tipo de tubogotejador. Verificou-se a influência causada pela indução forçada de precipitação química no coeficiente de variação de vazão (CVq), no desvio padrão, na vazão média e na taxa de redução de vazão dos emissores. Os resultados mostram que o tempo de funcionamento dos emissores influiu no CVq devido à ocorrência de obstruções tanto parcial como total. A obstrução do orifício de saída do tubogotejadores, decorrente do tempo de funcionamento, contribui para o aumento dos coeficientes de variação, constituindo um problema sério da irrigação localizada, pela desuniformidade de vazão causada.  UNITERMOS: Irrigação localizada, obstrução de emissores, sulfato de cálcio.   DIAS, N. da S.; OLIVEIRA, M. V. A. M. de; COELHO, R. D. CLOGGING RESISTANCE OF DIFFERENT DRIP LINE FOR CALCIUM CHEMICAL PRECIPITATION   2 ABSTRACT  To evaluate the drip line clogging susceptibility to chemical precipitate of calcium sulfate, a study was carried out in the Irrigation Laboratory of the Superior School of Agriculture " Luiz de Queiroz " (USP/ESALQ). Three different drip lines (Carbo Drip 2,30 L h-1 - T1; Hydro Gol, 2,00 L h-1 - T2 and Typhoon 1,70 L h-1 - T3)were used and installed in a 6 m long x 1.3 m wide x 1.45 m high dench. The influence caused by the chemical precipitation in the flow variation coefficient (CVq), standard deviation, medium flow and rate flow reduction of the emitters was verified. The results showed that the operation time of the emitters influences on CVq, due to occurrence of partial and total obstructions of emitters. Dripper exit obstruction due to operation time contributes to the increase of the flow rate variation coefficients, resulting in a serious problem in trickle irrigation.  KEYWORDS: Trickle irrigation, emitter clogging, calcium sulfate

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