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Hydrogen circulation pump is an important equipment for hydrogen fuel cell system which can recycle the unreacted hydrogen to improve the system efficiency. A mathematical model of claw pump is built and the internal flow field was simulated by dynamic mesh technology. The p-θ diagram is obtained by analyzing the gas flow characteristics. The model is firstly verified by air experiments and then the performance influenced by suction pressure, exhaust pressure, rotating speed, and clearance are analyzed. The volumetric efficiency increased by 22% when the suction pressure increases from 152 kPa to 168 kPa but decreased by 23% when the exhaust pressure increases from 172 kPa to 188 kPa. The volumetric efficiency increased by 26.7% when the rotating speed increases from 4000 rpm to 6000 rpm but decreased by 52.1% when the working clearance increases from 0.03 mm to 0.07 mm. Due to the range of working pressure ratio is small, the indicated efficiency changes slightly.

Natural gas quality assessment is a relevant issue. A critical analysis of calorimeter designs for measuring the calorific value of natural gas was carried out. The most common methods for determining the calorific value of natural gas are as follows: direct by gas calorimeters; indirect by gas chromatographs; indirect, based on correlations. The advantages of isoperibolic calorimeters of measuring calorific value of natural gas directly in the consumer’s conditions are substantiated. The design of a portable calorimeter containing a thermostated shell, calorimetric tank, Peltier element with tank, circulating pump, gas burner, thermostat systems, metered supply of natural gas and air, fuel ignition, sensors, combustion analyzer and control and measurement unit, was developed. The geometric dimensions of the calorimetric tank are optimized, materials and technologies of manufacturing parts are specified. The metrological analysis of the developed portable calorimeter was carried out. A method for measuring the calorific value of natural gas directly in the conditions of household consumers and transport enterprises was developed. The results of testing the prototype calorimeter in the laboratory confirmed its high performance and metrological characteristics, and the deviation of the measurement of the calorific value of natural gas from that determined using a gas chromatograph was 0.6%.

The relevance of the study is associated with the need to implement the concept of the scientific and technological development of the Russian Federation, which outlines the transition to environmentally friendly and resource-saving technologies. The paper presents the results of full-scale experiments of changes in the operating parameters of the experimental-industrial hybrid solar hot-water system with a circulating pump operating in periodic duty mode in the hydraulic circuit. The proposed hardware and software system provides switching on and switching out of the circulating pump depending on the temperature difference of the coolant in collectors and at the storage tank output. This provides the maximum thermal energy for the hot-water system at different of solar radiation intensities and the minimum power consumption by the circulating pump generated by solar panels.

Liquid Droplet Radiator (LDR) system is regarded as a quite promising waste heat rejection system for aerospace engineering. A comprehensive review on the state-of-the-art of LDR system was carried out. The thermal design considerations of crucial components such as working fluid, droplet generator and collector, intermediate heat exchanger, circulating pump and return pipe were reviewed. The state-of-the-art of existing mathematical models of radiation and evaporation characteristics of droplet layer from literatures were summarized. Furthermore, thermal designs of three LDR systems were completed. The weight and required planform area between the rectangular and triangular LDR systems were respectively compared and the evaporation models for calculating the mass loss were evaluated. Based on the review, some prospective studies of LDR system were put forward in this paper.

Дипломний проект першого (бакалаврського) рівня вищої освіти на тему: «Автономна опалювальна котельня для житлових будівель в м. Львові»: пояснювальна записка на 75 с., 13 рис., 11 табл., 15 бібліографічних найменувань; креслень – 3 арк. ф. А1. Мета проекту – створення проекту автономної котельні для житлових будівель. Використовуючи нормативні матеріали та каталоги фірм-виготовлювачів відповідної продукції, була розроблена і розрахована принципова схема автономної котельні та підібране основне і допоміжне обладнання. Для кліматичних умов міста Львів визначені теплові навантаження на опалення і гаряче водопостачання групи житлових будівель з заданими характеристиками і кількістю проживаючих в них людей. Наведені розрахунки витрат теплоти на опалення та гаряче водопостачання за точною методикою втрат теплоти у довкілля. Розглянута теплова схема котельні, за результатами розрахунків якої підібране відповідне обладнання: котли та насоси. Розглянута схема контуру мережної води вузла підживлення та вузла ГВП. Підібране відповідне обладнання: насоси мережної води, підживлення та ГВП. Відмічені основні заходи та засоби по організаційно-технічному забезпеченню охорони праці. На кресленнях наведені загальний вид теплообмінника системи гарячого водопостачання, схема компоновки тепломеханічного обладнання та теплова схема автономної котельні. Ключові слова: гаряче водопостачання, опалення, теплове навантаження, мережний насос, циркуляційний насос, охорона праці. Diploma project of the first (Bachelor) level of higher education on the theme: "Autonomous heating boiler house for residential buildings in Lviv": explanatory note for 75 p., 13 figures, 11 tables, 15 bibliographic names; drawings - 3 arcs. f. A1. The purpose of the project is to create a project of an autonomous heating station for residential buildings. Using regulatory materials and catalogs of manufacturers products was developed and calculated the schematic diagram of the autonomous heating point and selected its basic equipment. For the climatic conditions of the city of Lviv, the heat loads for heating and hot water supply of a group of residential buildings with the specified characteristics and the number of people living in them are determined. Calculations of heat consumption for heating and hot water supply are given. According to the exact method of heat loss in the environment. The thermal scheme of the boiler room is considered, according to the results of the calculations of which the appropriate equipment is selected: boilers and pumps. The scheme of the mains water circuit of the feeder unit and the hot water supply unit is considered. Appropriate equipment selected: mains water pumps, feed and hot water pumps. The basic measures and means on organizational and technical maintenance of labor protection are noted. The drawings show the general view of the heat exchanger of the hot water supply system, the layout of the thermomechanical equipment and the thermal diagram of the central heating point. Key words: hot water supply, heating, heat load, mains pump, circulating pump, labor protection.

Solar-powered LiBr absorption cooling system is of potential in the application of air-conditioning. A LiBr-H2O concentration difference cold storage system driven by vapor compression heat pump was proposed. This cold storage process is not affected by the environmental conditions, since the main energy input is low price electricity at night. The experimental results show that the energy storage density (ESD) can reach 77.8 kWh/m3 and the energy storage coefficient of performance (ESCOP) is 2.81 with low heat loss. The ESCOP means the energy stored in the cold storage process divided by the total electricity consumption in the absorption and heat pump subsystem. The heat transfer in the condenser of the absorption subsystem approximately equals that in the evaporator of the heat pump, and the electricity consumption of the circulating pump in the absorption subsystem is low. Therefore, the value of ESCOP should be slightly lower than the COP of the heat pump system but for higher than 1. These results indicate the feasibility of improving the system efficiency, the operation cost, and long term operation of the solar air conditioning system by coupling the absorption and vapor compression cooling cycles. Finally, the influence of working parameters on the system performance is discussed based on the experimental and simulation analyses. The energy balance between the absorption cycle and the heat pump cycle in the cold storage system is analyzed. It is found that the coefficient of performance of the heat pump (COPele,HP) and ESCOP increase with a low initial LiBr-H2O solution concentration. The ESCOP decreases by 34.4% when the initial concentration increases from 52% to 57%. The average ESD increases to 140.2 kWh/m3 with a concentration difference of 8%. Based on the experiment results, the payback period of the proposed system is estimated as 2.4 years comparing with the traditional LiBr-H2O absorption system.

The organic Rankine cycle is introduced into the conventional ejector refrigeration (CER) system to establish the low-grade heat-driven cooling/power cogeneration ejector refrigeration (CPC-ER) system using the isobutane as the refrigerant. In comparison with the CER system where external power is consumed by the circulating pump, the power output from the CPC-ER system is more than the power consumption of its circulating pump so that a portion of net power is derived from the CPC-ER system. Based on the mathematical model of thermodynamics, energy and exergy analysis of the CPC-ER system is carried out and compared with the CER system. The results reveal that the equivalent coefficient of performance (COP) of the CPC-ER system is 41.14% to 71.30% higher than that of the CER system, and the exergy efficiency of the CPC-ER system is 1.32 to 1.49 times higher than that of the CER system. Both the power produced by the turbine and the total exergy output from the CPC-ER system approach the maximum, as the generating temperature in the generator is up to 80°C. The CPC-ER system has the higher energy utilization efficiency than the CER system, and it is suitable for the cooling and power-required places with low-grade thermal sources.

A pump is needed in an ejector refrigeration system, which makes the system high cost and complicated and hinders its application. A pump-free double heat source ejector refrigeration system using R1234yf as working fluid is proposed in which an injector driven by another heat source replaces the liquid circulating pump, making the system more affordable, simpler and more stable. The effect of different operation conditions on entrainment ratios and the influence of different factors on system performance are analyzed on the basis of mass, momentum and energy conservation equations. The influence degree of each factor on system performance is investigated by the orthogonal test method. The condenser temperature has the largest effect on system performance. The pressure drop in the suction chamber of gas-liquid injector has the least impact on system performance. The COP can reach about 0.35 under a certain working condition. The system can be driven by two different temperature heat sources with no electricity needed, and it is a good choice for places with abundant heat resources or lack of electricity.

Polymer electrolyte membrane fuel cell (PEMFC) is one of the promising solutions overcoming future energy crisis and environment pollution in the automotive industry. However, PEMFC is vulnerable to the circulation of hydrogen mass flow rate and pressure, which may cause the degradation of the PEMFC's anode components and reduction of output performance over time. Thus, the control of the hydrogen supply system draws attention currently and is critical for the durability and stability of the PEMFC system. In this study, a model predictive control (MPC) approach for hydrogen circulation system is developed to regulate the hydrogen flow circulating. A model of the hydrogen supply system that contains a flow control valve, a supply manifold, a return manifold and a hydrogen circulating pump is firstly developed to describe the behavior of the hydrogen mass flow dynamics in the PEMFC. Subsequently, a hydrogen circulating pump MPC scheme is designed based on the piecewise linearized model of hydrogen circulation as well as the switched MPC controllers. By predicting the pressure of the return manifold and the angle velocity of the pump, the proposed MPC approach can manipulate the hydrogen circulating pump to achieve efficient and stable operation of the PEMFC.

The ventilator of the heating tower and the circulating pump of the anti-freeze solution are the main electrical equipment of a heating tower heat pump system, besides the compressor. By controlling the working frequencies of the ventilator of the heating tower and circulating pump of the anti-freeze solution, the effects of the operation parameters of a closed-type heating tower on its heat absorption and the performance of heating tower heat pump system were investigated under winter heat conditions. The results indicated that reducing the frequency of the circulating pump for the anti-freeze solution leads to a decrease in the temperature of the outlet evaporator of the anti-freezing solution and an increased temperature difference between the anti-freeze solution flowing into and out of the heating tower; meanwhile, excessively high and low anti-freeze flow rates lead to reduced heat absorption of the closed-type heating tower. The coefficient of performance fluctuates slightly if the frequency of circulating pump is above 20 Hz, but a slight drop in coefficient of performance is observed when the frequency is less than 15 Hz. The system energy efficiency ratio tends to increase as the frequency of circulating pump is reduced, although a substantial reduction occurs at 10 Hz. Furthermore, a reduced ventilator frequency decreases the temperatures of the anti-freeze solution at the inlet and outlet of the heating tower and the temperature difference, hindering the heat absorption of the heating tower. With reductions in the ventilator frequency, the coefficient of performance exhibits an initial increase followed by subsequent decreases, while the system energy efficiency ratio showed continual increases until the ventilator frequency dropped to 10 Hz. When the ventilator frequency or circulating pump frequency drops to 15 Hz and 10 Hz, the evaporation temperature of the heat pump unit decreases, resulting in an excessively exhaust temperature, which is not favorable for the safe operation of the system.

Príspevok sa venuje porovnaniu hydraulických pomerov v primárnych rozvodoch tepla vybraného úseku sústavy centralizovaného zásobovania teplom. Porovnával sa výpočtový stav so skutočným stavom pred obnovou stavebných objektov a výpočtový stav s predpokladaným stavom po obnove stavebných objektov pripojených na sústavu centralizovaného zásobovania teplom. Cieľom príspevku je prostredníctvom tlakových diagramov poukázať na disproporcie, ktoré sú na reálnych tepelných sieťach sústav centralizovaného zásobovania teplom, nakoľko sa hydraulike vonkajšej časti vykurovacej sústavy nevenuje dostatočná pozornosť. Rekonštrukciou pôvodných primárnych rozvodov tepla a výmenou obehového čerpadla na vybranom úseku možno dosiahnuť hydraulickú stabilitu sústavy a úsporu prevádzkových nákladov. The paper deals with the comparison of hydraulic conditions in the primary heating network of a selected section of the district heating system. The calculated state was compared with the actual state before the renovation of buildings and the calculated state with the expected state after the renovation of buildings connected to the district heating system. The aim of the paper is to point out the disproportions that exist in the real heating networks of district heating systems through pressure diagrams, as the hydraulics of the outer part of the heating system are not given sufficient attention. By reconstructing the original primary heat distribution and replacing the circulation pump on a selected section, hydraulic stability of the system and savings in operating costs can be achieved.

In this study we are obtaining the maximum temperature of solar water heater using of PV cells. The flat plate solar water heater are consisting using several parts such as collector , flat plate glass , circulating pump, PV cells , frame . The centrifugal pump is operated by PV Cells. Water temperature is measured by digital temperature meter. Hot water is storage in container. The most elements of these are a clear front cover, collector housing associated an absorbent material.

Solar water heater is a device which is used for heating the water using of sun energy. This system is connected like as storage tank, centrifugal pump, pipes and glass. The circulating flexible water pipes are connected with the metallic pipe, which are assembled with the body. The solar radiation are achieving from sun and passing although glass and collector for the purpose of the heating the circulating water. In this way we are achieving the various temperatures using of circulating pump.

In this study, we are achieving the hot water from solar water heater. The solar water heater are archiving the solar radiation from sun energy after that we are obtaining the hot water, in this way we are obtained the various temperatures of hot water with the help of circulating pump, the pump are used for obtaining the various flow rate of using water. The solar water heater is having several parts such as collector, pipe, water container and pump.

This article experimentally investigates the performance of two control methods (the supply water temperature method and the water flow control method)for a direct-ground cooling system. The control methods were implemented through three types of indoor feedback controllers: 1)an on/off controller, 2)an on/off controller with a deadband and 3)P controller. The performances of the control methods were evaluated regarding room temperature stability and pump energy use. Ceiling cooling panels were employed to keep the test room air temperature at 25.0 °C under periodic heat gain conditions. The cooling system used a ground heat exchanger with a U-pipe in an 80-meter-deep borehole as a cooling source. The findings show that room air temperature was maintained close to the set-point with both control methods, but it was more stable with the temperature control method. In addition, condensation risk was easily preventable with the temperature control method. A parametric study showed that pump energy use when using two-position controllers could be as low as when using modulating controllers if the on-state flow rate of the circulating pump is selected in relation to the ground temperature and heat transfer characteristics of the heat exchanger.

An integrated system to support the functioning of a wind-solar electric system has been designed, based on predicting a change in the capacity of a rechargeable battery when measuring voltage at the input to a hybrid charge controller, voltage at the output from an inverter and the frequency of voltage. Taking preliminary decisions to support the capacity of a rechargeable battery related to a change in the capacity of a thermoelectric battery is based on establishing the ratio of voltage at the input to a hybrid charge controller to voltage at the output from the inverter, which are measured. A change in the rotational speed of the electric motor of the circulating pump has been ensured in terms of changes in consumption and the temperature of heated water by reducing charge duration by up to 30%. An integrated mathematical and logical modelling of a wind-solar electric system has been performed, based on the mathematical substantiation of the architecture of a technological system and the mathematical substantiation to support the operation of a wind-solar electrical system. The basis for the proposed technological system is a dynamic subsystem that includes the following components: a wind-energy installation, a photoelectrical electrical module, a hybrid charge controller, and an inverter, an array of rechargeable batteries, a thermoelectric battery. The time constants and the coefficients for mathematical models of the dynamics have been determined related to a change in the capacity of a rechargeable battery, the rotational speed of the electric motor of the circulating pump, and consumption of local water. A functional assessment has been derived for a change in the capacity of a rechargeable battery, the rotational speed of the electric motor of the circulating pump, consumption of local water related to a change in the temperature of local water in the range of 30–70°C. Defining the resulting functional information on forecasting a change in the capacity of a rechargeable battery makes it possible to take the following preliminary decisions: about changing the rotational speed of the electric motor of the circulating pump, about changing the consumption of local water. Maintaining the capacity of a rechargeable battery is carried out based on adjusting the generation and consumption of energy.

The analysis was conducted for the optimal operation under off-design conditions of the indirect dry cooling thermal power generating unit. The numerical model of natural draft dry cooling tower (NDDCT), as well as the off-design performance model of whole thermal system of a supercritical power generating unit, including that of turbine, condenser and regenerative system, were combined together. An iterative procedure was adopted so that the operating parameters of dry cooling system with cooling water mass flow rate and output power load were obtained. The total coal consumption of power generation, which considered both effects of back pressure of turbine and power consumption of circulating pump, was taken as the optimization object. The results indicated that the pump power consumption increased, while the back pressure decreased with circulating cooling water mass flow rate. There was the optimum cooling water mass flow rate corresponding to the lowest coal consumption of power generation. For the objective power generating unit, 4.83 ton standard coal per hour at most can be saved by adjusting the circulating cooling water flow rate to the optimum value.

This paper addresses the challenges the policymakers face concerning the EU decarbonization and total electrification roadmaps towards the Paris Agreement set forth to solve the global warming problem within the framework of a 100% renewable heating and cooling target. A new holistic model was developed based on the Rational Exergy Management Model (REMM). This model optimally solves the energy and exergy conflicts between the benefits of using widely available, low-temperature, low-exergy waste and renewable energy sources, like solar energy, and the inability of existing heating equipment, which requires higher exergy to cope with such low temperatures. In recognition of the challenges of retrofitting existing buildings in the EU stock, most of which are more than fifty years old, this study has developed a multi-pronged solution set. The first prong is the development of heating and cooling equipment with heat pipes that may be customized for supply temperatures as low as 35 °C in heating and as high as 17 °C in cooling, by which equipment oversizing is kept minimal, compared to standard equipment like conventional radiators or fan coils. It is shown that circulating pump capacity requirements are also minimized, leading to an overall reduction of CO2 emissions responsibility in terms of both direct, avoidable, and embodied terms. In this respect, a new heat pipe radiator prototype is presented, performance analyses are given, and the results are compared with a standard radiator. Comparative results show that such a new heat pipe radiator may be less than half of the weight of the conventional radiator, which needs to be oversized three times more to operate at 35 °C below the rated capacity. The application of heat pipes in renewable energy systems with the highest energy efficiency and exergy rationality establishes the second prong of the paper. A next-generation solar photo-voltaic-thermal (PVT) panel design is aimed to maximize the solar exergy utilization and minimize the exergy destruction taking place between the heating equipment. This solar panel design has an optimum power to heat ratio at low temperatures, perfectly fitting the heat pipe radiator demand. This design eliminates the onboard circulation pump, includes a phase-changing material (PCM) layer and thermoelectric generator (TEG) units for additional power generation, all sandwiched in a single panel. As a third prong, the paper introduces an optimum district sizing algorithm for minimum CO2 emissions responsibility for low-temperature heating systems by minimizing the exergy destructions. A solar prosumer house example is given addressing the three prongs with a heat pipe radiator system, next-generation solar PVT panels on the roof, and heat piped on-site thermal energy storage (TES). Results showed that total CO2 emissions responsibility is reduced by 96.8%. The results are discussed, aiming at recommendations, especially directed to policymakers, to satisfy the Paris Agreement.

Taking the solar hot water circulation process in absorption refrigeration as the research object, two temperature control strategies are proposed according to the operating temperature range of working pairs in the generator, and the model of solar hot water circulation is built. The tilt and azimuth of solar collector are optimized according to the maximum radiation amount per unit area of collector with Hooke-Jeeves algorithm. The area of collector is optimized according to the solar fraction specification value with 0.5. The volume of the heat storage tank is optimized according to the maximum solar fraction and minimum start stop times of generator circulating pump. The optimization method proposed can guide the design of solar hot water circulation system for solar absorption refrigeration.

In semiconductor integrated circuit manufacturing, lithography, etching, physical vapor deposition, chemical vapor deposition and other processes, which need to use chiller for precise temperature control of process chamber. The special chiller for semiconductor industry is used to meet the process requirements of large load change and precise temperature control. The special chiller for semiconductor industry is composed of refrigeration system and circulation system. The refrigeration system includes four main parts: compressor, condenser, electronic expansion valve and evaporator, the circulation system is composed of water tank, circulating pump and heater. The system of chiller is a multivariable, nonlinear and time-varying complex system. The temperature control of chiller is affected by compressor frequency, evaporating pressure, suction pressure, heating power and other parameters, it is difficult to establish a mathematical model accurately. The traditional PID control is difficult to meet the control needs. Therefore, fuzzy PID control is adopted. Fuzzy control is applied to improve the system response when the system error is larger, and conventional PID regulator is used when the system error is smaller. The parameters of PID control are changed by using the idea of fuzzy PID, and PID control action is adjusted according to different error situation and control cycle, thereby, reasonable control and regulation of temperature are achieved.

The aim of this work is to develop dual purposes solar heating system using a heat pipe evacuated tube solar collector. The heat transfer fluid between the thermal loads and the solar collector loop was heating oil. The study provided two thermal loads; a solar water heating system and a solar baking/cooking system that had experimentally investigated under various weather conditions. The experimental pilot unit was installed in the Solar Energy Department, National Research Centre, Giza, Egypt. Several test runs were performed to measure all assigned parameters that affect the system performance. The system is designed to provide hot oil surrounding the inner vessel of the baker with a temperature up to 250o C while the raw food can be baked/cooked and the outlet thermal energy can be used for heating water via an immersed coil in the hot water storage tank; then the relatively cooled oil is returned to the solar collector via hot oil circulating pump. The tested system can be positively contributed to baking and cooking purposes and providing hot water as well. It is considered an environmentally friendly system and can significantly enhance sustainable communities. The system is capable to produce hot water temperature up to 85 oC and an average temperature of about 60 oC during the day which is suitable for residential purposes and industrial process as well The auxiliary heating system can be an electric source in case of using in urban areas and can be renewable energy source like biogas or hydrogen fuels in rural and isolated areas.

This paper focuses on the optimal design of PV/T modules implementing roll-bond absorber. A dedicated tool including detailed pressure loss calculation and flow distribution in the absorber was developed to compare different design layouts (harp, serpentine and spiral) and channel sizes. The tool was calibrated against experimental data which confirmed its reliability to predict both electric and thermal performance. The model results outlined the importance of the circulating pump power consumption in the identification of the optimal configuration. The harp design achieves the best performance with 57.1% and 17.0% first law and net exergy instantaneous efficiency respectively assuming a 25 °C fluid inlet temperatures and NOCT conditions. The serpentine configuration achieves the highest thermal efficiency of 46% but suffers higher pressure drop which penalize the net power output of the system. Two innovative harp designs are proposed to reduce the hot spot connected to the junction box and uneven fluid distribution. Finally, the inlet fluid temperature has a strong influence on the flow rate inside the absorber affecting the optimal design option.

In daily usage of water heater, residual cold water stored in water pipe have to be emptied before hot water come out from water heater, which cause considerable waste of water, especially there exists long water pipe. Therefore, it is crucial to solve the water wastage, and of great significance to protect water resource as the demand for water is continuously increasing. This paper presented a water circulating system which can recycle the residual cold water stored in water pipe to water heater using water circulating pump, electromagnetic valve, controlling system and water circulating pipe. After cold water is heated in water heater and reach the required temperature set by user, it will run automatically to the outlet. This water circulating system can be applied to domestic water heater, which can save enormous water resource, and it has prosperous future profit prospect.

This article presents the basics of the mathematical analysis for determining the COP (coefficient of performance) optimum of a heat recovery system. A new sizing method is introduced to determine the optimal mass flow of hot water and well water and thus the optimal performance of the circulating pump. The optimal pump performance ensures maximum energy efficiency of the system, i.e. maximum coefficient of performance (COP) of the heat pump recovery system with using the chosen type of heat pump. The mathematical model of the heat recovery system is stationary, consisting of algebraic equations with lumped parameters. By using the analytical optimization procedure and the objective function, the local energy optimum conditions can be defined as a result, with respect to the mass flow. The governing equations for local optimization of the COP are presented in this paper. The resulting system of algebraic functions can only be solved numerically. For this purpose, Newton linearization and Gauss elimination methods should be used, which will be presented in the upcoming papers.

Based on the shear stress transport (SST) turbulence model, the influence of different outlet pipe angles on the head and efficiency of a boiler circulating pump was analyzed. When the outlet pipe angle changed from 115&deg, to 130&deg, the head and efficiency of the pump reduced significantly. The boiler circulating pump with 115&deg, outlet pipe angle was selected as the further research object, and the reliability of the numerical simulation was verified by experiments. The transient flow of the prototype pump under the design flow rate condition (1.0Qd) and four other flow rate conditions (0.6Qd, 0.8Qd, 1.2Qd, and 1.4Qd) was studied. The results show that, under the conditions of design flow and large flow rate (1.0Qd, 1.2Qd, and 1.4Qd), the centrality and regularity of radial force distribution are obviously better than those of small flow rate (0.6Qd, 0.8Qd). The leakage of the rear seal ring is less than that of the front seal ring under five flow rate conditions. As the flow rate increases, the leakage of front and rear seal rings decreases, and the leakage ratio of front and rear seal rings increases. The energy loss of the rear cover plate is greater than the energy loss of the front cover plate under five flow rate conditions. With the increase in flow rate, the total loss energy of the prototype pump decreases first and then increases, and the energy loss of the disc becomes larger and larger.

The application of hydroponic farming methods has been widely applied by the community, the system used is still manual so that it lacks quality, both in terms of humidity and growth. For that we need a system that is able to regulate the time of watering and the provision of nutritional solutions automatically without disturbing the activity. In the design of an automatic DFT hydroponic system using an Android Arduino based solar panel. Where the solar panel system functions as a renewable energy substitute for PLN which will fill the accumulator. The accumulator filling process is equipped with a solar charge controller module, which aims to avoid overcharging the accumulator. The process of watering and administering nutritional solutions is controlled by the Arduino UNO microcontroller which is integrated with the DS1307 RTC module, the HC-05 bluetooth serial communication module and the android smartphone application as the relay module to turn on and turn off the circulation pump according to a predetermined schedule. Test results and tool performance are in accordance with the plan, namely the efficiency of the use of solar panels. This is indicated by scheduling the circulation of the circulating pump for 1 hour from the estimated calculation of the maximum pump speed for 2.38 hours. In testing the transmission of data from bluetooth HC-05 connected to a bluetooth smartphone with unhindered conditions obtained a maximum distance of 15 meters and with a concrete wall obstruction a maximum distance of 5 meters, with plywood walls a maximum distance of 8 meters.

The influence of vortex on steady flow and pressure fluctuation of circulating axial pump under pump condition is illustrated by numerical method validated by experiment measurement, a method for analyzing vibration by using Euler head density function (EHDF) is established. Based on the matching equation of the flowing angle of impeller and guide vane, two groups of guide vanes are designed to relate the same impeller as comparison. When the stagnation point at the guide vane inlet is offset, the low-speed vortex (LSV) is generated in the area from the mid flow surface to the hub surface, where the local Euler head (LEH) curves’ distribution is disarranged and the EHDF of this part is larger and closes to the EHDF value of the whole spanwise region, furthermore, the pressure fluctuation levels of low frequency band here deteriorate seriously. The larger EHDF value means the flow state and pressure fluctuation are worse, and the mainly developing of LSV is in this problematical area where the EHDF value has deteriorated the most. With quantizing image analysis of vorticity and LEH of the circulating pump by the EHDF, the structure position of LSV can be analyzed and the vibration level can be predicted.

In a water-cooled thermoelectric generator (TEG) system, there is an energy-consuming circulating water pump. In order to reduce pump energy consumption caused by backpressure and increase the output power of the entire system, combining numerical simulation and experimentation is adopted to explore the suitable coolant flow rate. Due to the limitations of the experimental conditions, numerical simulation is used to compute the temperature distribution and flow field inside the TEG. Base on the numerical results and the empirical formula, the circulating pump energy consumption is calculated. The maximum power output of the thermoelectric module (TEM) at the corresponding temperature difference is obtained by experiment. Finally, the maximum net output power of the module is revealed and the relationship between the coolant flow rate and average temperature of the hot end of the TEMs is proposed, which can serve as a theoretical basis for cooling water flow rate management of the TEG system.

This paper proposes a realistic demand side management mechanism in an urban district heating network (DHN) to improve system efficiency and manage congestion issues. Comprehensive models including the circulating pump, the distribution network, the building space heating (SH) and domestic hot water (DHW) demand were employed to support day-ahead hourly energy schedule optimization for district heating substations. Flexibility in both SH and DHW were fully exploited and the impacts of both weekly pattern and building type were modelled and identified in detail. The energy consumption scheduling problem was formulated for both the individual substations and the district heating operator. Three main features were considered in the formulation: user comfort, the heat market and network congestion. A case study was performed based on a representative urban DHN with a 3.5 MW peak thermal load including both residential and commercial buildings. Results show an up to 11 % reduction of energy costs. A sensitivity analysis was conducted which provides decision makers with insights into how sensitive the optimum solution is to any changes in energy, user comfort or pumping costs.

As one of the future directions of nuclear energy development, small modular reactor (SMR) designs meet the demands of safety, sustainability, and efficiency by eliminating circulating pump...

Air source heat pumps (ASHPs) are in wide use around the world, and their practical applications and continual improvement have attracted great attention. To more fully understand their actual-operational performance, field monitoring was carried out on 103 ASHP systems in Beijing during the 2018–2019 heating season, accompanied by a decoupling analysis of the key influencing factors on performance. The observed seasonal coefficient of system performance (SCOP) ranged from 1.54 to 2.95, with an average of 2.21. Based on this large sample, three key influencing factors were identified, namely: terminal type, operating load rate and capacity regulation characteristics. In terms of terminal type, floor heating systems obtained a relatively high SCOP of 2.37 on average, due to the lower water temperature, compared with a radiator system average of 2.10. As for load rate, oversized capacity is a common problem: the recorded average annual operating load rate was only around 0.48, which resulted in high energy consumption from frequent on–off losses, and also increased power consumption by the circulating pump. This analysis provides engineering reference and support for the design and technological improvement of ASHP systems.

Destructing thermal stratification of water storage tank and effect on solar collector performance was investigated experimentally. First experiment was performed using conventional thermosyphon flow of water. In the second experiment, without discharging the hot water storage tank of the previous day, the experiment was continued. Third and fourth experiments were started with similar condition to the first case. However, in the third case during the experiment, the tank’s water mixed using a circulating pump and in the fourth case, fresh water was replaced at three different times with the same amount from tank’s water. Results indicated lowering the temperature of the lower layers in the tank would enhance the solar collector performance. Collector performed accordingly from best to worst; the three times tank discharge, conventional, water flow circulation, and initially charged tank recharge. For example, at 16:00, the collector’s efficiencies for three-time tank discharge, normal, and destruction of thermal stratification experiments were 52.9%, 38.3%, and 32%, respectively. Further, at 17:00, the collector’s efficiency for three-time discharge indicated 36% while nearly zero for other experiments was obtained. In addition, for heat absorption and collector’s efficiency study, the theoretical results compared with the experimental results.

During the operation of water wells, their specific production rate is reduced as a result of mechanical, biological and chemical colmatage. The extraction of the mudding element from the filter is complicated by the fact that the deposits cover not only the well filter, but also gravel package and are not completely removed by the treatment. An installation is proposed for reversereagent regeneration of water wells, consisting of a compressor, hoses and submersible device in the form of a two-chamber pneumatic displacement pump. The advantage of the unit is the absence of a circulating pump in its composition and the possibility of efficient processing of the limited filter interval. The downhole submersible device does not contain moving parts except for two floating check valves. In order to describe the process of dissolution of deposits by the method of reverse-reagent water well regeneration, a system of equations is used: the combined equation of motion and mass conservation and the generalized equation of kinetics. By integrating the kinetics equation, an analytical dependence is obtained to calculate the operating time of the unit for reverse-reagent filter regeneration, followed by the reducing of the specific volume of the colmatizing deposits in the gravel package to a predetermined level. According to the formulas obtained, a computer program was compiled, which allows calculating the number of operating cycles of the device, the duration of cleaning and the degree of removal of the colmatant at each stage of the work. With the aid of the developed computer program, the operation of the unit for reverse-reagent filter regeneration is considered on behalf of a water well using two different reagents: hydrochloric acid and sodium dithionite. The procedure for calculating the amount of reagent needed to restore water well productivity is presented.

Under reduced ambient temperatures, a low rotational frequency of a cranked shaft of a carburettor engine during its start-up stipulates the decrease in the parameters of the compression stroke end (pressure and temperature), which has a significant impact on the conditions of preparation of fuel and air mixture for ignition in cylinders. The decrease in pressure of gasoline saturated vapours together with low velocities of passage in an intake manifold significantly deteriorate the conditions for gasoline evaporation and combustible mixture formation with required combustion limits. In addition, the reduction in the rotational frequency of the cranked shaft of the engine affects the operation of the ignition system, which leads to the decrease in the reliability of spark formation. Therefore, the engine should be warmed-up before its starting.Preheating of the cooling fluid is one of the most common and most effective individual methods of engine warming-up at reduced temperatures. Such heaters are suitable for almost all types of vehicles; therefore, they are used in cars, trucks, buses, aircrafts, yachts and boats.However, in spite of broad possibilities, pre-heaters have not yet found mass application. The main reason that reduces the advantages of pre-heating is non-autonomous operation of the heater components: a fuel pump, a fan for supplying air to the combustion chamber, a circulating pump for pumping a liquid heating medium, which often results in “deep” discharge of a rechargeable battery and prevents the vehicle from starting, in general.In order to avoid the battery discharge during preheating, it is reasonable to use the thermoelectric generator as a source of electricity for the heater components.The design of a gasoline-operated thermoelectric heater for vehicle pre-heating with the engine capacity of 4-10 litres has been developed in this paper. The conditions ensuring the maximum electric power and efficiency of the device have been determined using computer design methods.Based on the results of computer simulation, it is shown that the use of the thermoelectric generator ensures an autonomous operation of the components of the heaters and allows solving the problem of car battery discharging during pre-start equipment operation

In this paper, we are studying about solar water heater. The solar water heater are consisting of several components such as circular pipe, flexible pipe, and metallic container for water and circulating pump. We are analyzed the outlet temperatures of hot water using of various flow rate (in liters/ Minutes).

Compared with the hydraulic configuration based on the conventional central circulating pump, a district heating system with distributed variable-speed-pumps configuration can often save 30–50% power consumption on circulating pumps with frequency inverters. However, the hydraulic regulations on distributed variable-speed-pumps configuration could be more complicated than ever while all distributed pumps need to be adjusted to their designated flow rates. Especially in a multi-source looped structure heating network where the distributed pumps have strongly coupled and severe non-linear hydraulic connections with each other, it would be rather difficult to maintain the hydraulic balance during the regulations. In this paper, with the help of the advanced automation and information technologies, a new hydraulic regulation method was proposed to achieve on-site hydraulic balance for the district heating systems with distributed variable-speed-pumps configuration. The proposed method was comprised of a new hydraulic model, which was developed to adapt the distributed variable-speed-pumps configuration, and a calibration model with genetic algorithm. By carrying out the proposed method step by step, the flow rates of all distributed pumps can be progressively adjusted to their designated values. A hypothetic district heating system with 2 heat sources and 10 substations was taken as a case study to illustrate the feasibility of the proposed method. Two scenarios were investigated respectively. In Scenario I, the flow rate of one substation varied according to its heat demand and the flow rates of other substations maintained their original values. And in Scenario II, the flow rates of all substations varied synchronously with the same relative rate. The results of the both scenarios indicated that all pumps could be properly adjusted to their designated flow rates by the proposed method with a high frequency adjustment resolution as 0.001 Hz. In scenario I, compared with the district heating system with distributed variable-speed-pumps configuration, the power consumption would be 26.6–66.8% less than that of the conventional central circulating pump configuration during the 4 rounds of regulations. In scenario II, the energy saving ratio of the district system with distributed variable-speed-pumps configuration would be 36.1–90.3% less than that of the conventional central circulating pump configuration during the 5 rounds of regulations.

The distributed variable-frequency speed pump (DVFSP) district heating system is not only to set circulating pump in the heat source, but also to set booster pumps in the heating pipeline network. All pumps adopt frequency conversion control. Compared with the traditional centralized power heat supply system, the distributed variable-frequency speed pump district heating system has more advantages in solving the hydraulic imbalances and improving the energy-saving rate of the heating system. In China the application of distributed variable speed pumps in the district heating (DH) network has been considered as a technology improvement that has a potential of saving energy, compared to the conventional central circulating pump (CCCP) DH system. In order to analyze the factors affecting energy-saving rates and pipe network balance mathematical analytical method is used in this paper. In the conclusion, how to further improve the energy saving rate will be put forward together with the improvements for hydraulic stability balance as a reference of optimized engineering design.

Organic Rankine cycle (ORC) is one of the most promising methods for converting medium-low temperature thermal energy into power. Many studies have been performed to optimize the operating conditions, select proper working fluids, design efficient expansion machines, etc. However, as the major power-consuming component in ORC system, the circulating pump is rarely studied. Most of theoretical studies only assume a constant value of isentropic efficiency for the compression process, but this value varies with different studies. A small-scale ORC system is built in the present work to test the performance of a diaphragm pump, and the working fluids of R245fa, R123, R152a and R600a are tested under various conditions. The isentropic efficiencies of diaphragm pump for compressing those working fluids are between 57.22% and 93.51%. The results show that volume flow rate and pressure difference have great influence on isentropic efficiency, and the isentropic efficiency increases with the volume flow rate and pressure difference. Under the condition of same volume flow rate and pressure difference, the isentropic efficiency conforms to the order of η R245fa > η R123 > η R600a > η R152a . The analyses about the variation trend of isentropic efficiency are made from the perspectives of physical properties of working fluid and the driving mode of diaphragm pump, which prove that the hitting velocity of diaphragm to the liquid is the main cause for irreversible enthalpy increment. A novel parameter α V / ρc p is proposed to identify the influence of physical properties of working fluid on the performance of pump. The experimental results show that under same volume flow rate and pressure difference, the isentropic efficiency of pump decreases with the increment of α V / ρc p of different working fluids.

The paper deals with the three-dimensional theoretical and numerical investigation of the electrical performance of a Photovoltaic System (PV) with active fluid cooling (PVFC) in order to increase its efficiency in converting solar radiation into electricity. The paper represents a refinement of a previous study by the authors in which a one-dimensional theoretical model was presented to evaluate the best compromise, in terms of fluid flow rate, of net power gain in a cooled PV system. The PV system includes 20 modules cooled by a fluid circulating on the bottom, the piping network, and the circulating pump. The fully coupled thermal and electrical model was developed in a three-dimensional geometry and the results were discussed with respect to the one-dimensional approximation and to experimental tests. Numerical simulations show that a competitive mechanism between the power gain due to the cell temperature reduction and the power consumption of the pump exists, and that a best compromise, in terms of fluid flow rate, can be found. The optimum flow rate can be automatically calculated by using a semi-analytical approach in which irradiance and ambient temperature of the site are known and the piping network losses are fully characterized.

The use of resource critical materials such as rare earth magnets in electrical machines has a negative impact on resource efficiency and production costs. Strict EU efficiency standards have led to the use of rare earth magnets in rotors in modern circulating pumps and thus represents the state of the art. This paper presents a resource saving design for circulating pumps. The combination of a synchronous reluctance motor with integrated ferrite magnets in the flux barriers of the rotor and a new thin-walled can provide a good basis for improving resource efficiency and power density.

In densely inhabited urban areas, deep borehole heat exchangers (DBHE) have been proposed to be integrated with the heat pump in order to utilize geothermal energy for building heating purposes. In this work, a comprehensive numerical model was constructed with the OpenGeoSys (OGS) software applying the dual-continuum approach. The model was verified against analytical solution, as well as by comparing with the integrated heat flux distribution. A series of modeling scenarios were designed and simulated in this study to perform the DBHE system analysis and to investigate the influence of pipe materials, grout thermal conductivity, geothermal gradient, soil thermal conductivity, and groundwater flow. It was found that the soil thermal conductivity is the most important parameter for the DBHE system performance. Both thermally enhanced grout and the thermally insulated inner pipe will elevate the outflow temperature of the DBHE. With an elevated geothermal gradient of 0.04 °C m−1, the short-term sustainable specific heat extraction rate imposed on the DBHE can be increased to 150–200 W m−1. The quantification of maximum heat extraction rate was conducted based on the modeling of 30-year-long operation scenarios. With a standard geothermal gradient of 0.03 °C m−1, the extraction rate has to be kept below 125 W m−1 in the long-term operation. To reflect the electricity consumption by circulating pump, the coefficient of system performance (CSP) was proposed in this work to better quantify the system efficiency. With the typical pipe structure and flow rate specified in this study, it is found that the lower limit of the DBHE system is at a CSP value of 3.7. The extended numerical model presented in this study can be applied to the design and optimization of DBHE-coupled ground source heat pump systems.