Pump System Research Articles

Experimental study on electricity generation performance of T‐type direct‐expansion solar PVT heat pump system

AbstractFocusing on the electricity generation performance of a direct expansion solar PVT heat pump system, a novel T‐type optimized collector/evaporator was designed. The experiment used refrigerant R410a as the working medium and was conducted under the average winter ambient temperature of 16°C in Fuzhou. Through experimental comparison, the differences in panel temperature, electricity generation, and efficiency under different radiation intensities were tested against traditional PV panels and honeycomb PVT panels. The experimental results showed that the T‐type PVT system exhibited significant advantages under various weather conditions. The back panel temperature was reduced by 12.74, 8.52, and 13.06°C compared to traditional PV panels and honeycomb PVT panels, respectively, and it maintained a stable increase in electricity generation. The maximum instantaneous electricity output increased by 56.6% relatively, and the total electricity generation increased by 9.3% to 14.5% compared to traditional PV panels. The photoelectric efficiency reached 21.54% and 22.6%, surpassing traditional PV panels and honeycomb PVT panels, with measured values relatively increased by 1.7%, 2.38%, and 2.76%, respectively. Economic evaluation indicated that the T‐type PVT system could save on self‐generated electricity costs, achieving savings of up to 386.50 and 210.81 yuan/year compared to traditional PV panels and honeycomb PVT panels. The T‐type PVT system demonstrated clear advantages in self‐generated electricity costs, significantly reducing costs for application scenarios and providing strong support for the practical application of renewable energy technologies.

External Support for Solar-Powered Water Pumping Systems in Rural Areas: A Systematic Review.

The Sustainable Development Goals emphasize coordination and integration between sectors. Solar-powered submersible water pumping systems are versatile technology that help address community drinking water, irrigation, and electricity needs. Stakeholders external to the community, particularly solar photovoltaic experts, are vital in ensuring continued system services; however, there has been no comprehensive assessment of different solar-powered water pumping system support efforts. This review is the first to systematically evaluate external support for solar-powered systems from multiple regions and implementing organizations. We reviewed solar-powered water pumping system literature to identify implemented external support and factors that affect implementation. Publication databases, organization Web sites, and citations were searched. Seventy-four studies were included and evaluated using inductive coding and thematic synthesis. We derived a framework that organized support activities and factors into three nested levels of implementation: system, program, and sector. For support efforts implemented after 2010, most support providers worked at all levels. Each provider type worked at levels aligned with their knowledge and resources and complementary to other providers' work. Drivers of support specific to solar-powered water systems were the existence of solar photovoltaic markets and infrastructure, support providers experienced with solar photovoltaics, and government and community solar advocates. We grouped support factors that study authors associated with system functionality into four categories: location and quality of support, reliability of support arrangements, frequency and timeliness of support, and policy and regulatory environment. No study outlined support for multiple uses of the systems or end-of-lifecycle care of solar panels. Solar-powered water pumping systems provide multiple community services, and their management will be bolstered by support providers collaborating to optimally apply their skill sets and create support plans that comprehensively address system versatility.

Implementation of Energy-saving Technologies in House construction

Objective. Over the past decades, heat pumps have gained great popularity due to their advantages in energy efficiency and environmental friendliness, becoming one of the most attractive alternatives to replace traditional heating systems running on fossil fuels. Heat pump efficiency is a decisive factor that should be taken into account when selecting and optimizing a heat pump system. The aim of the study was to evaluate the efficiency of air source heat pumps of the air-to-water system in the climatic conditions typical of the regions of the Central Federal District. Method. To evaluate the efficiency of air source heat pumps, a mathematical model is used that takes into account the multifactorial nature of the process under study. Result. To adequately compare the obtained research results with the passport performance indicators, the transformation coefficient (COP) was used, showing the ratio of the energy received to the expended work. As a result, the method of heating rooms with an air source heat pump with a combined operation mode was recognized as more preferable. Conclusion. Currently, the potential of heat pumps in the field of energy saving and CO2 emission reduction remains largely untapped, which sets the vector for further research.

CFD analyses and model tests for the optimization design of a large mixed-flow pumping system

Abstract Aiming at the optimization design of the pumping system with mixed-flow pumps, a serial of comparative hydraulic tests, numerical simulation and physical model tests were carried out. The comparative hydraulic test results of suction and discharge passages showed that the design scheme proposed by authors had better flow patterns and smaller hydraulic loss. The comparative CFD analyses indicated that the internal flow in the elbow-type suction box designed by authors were smoother and the flow conditions generated for pump were slightly better, but the flow distribution on both sides of partition pier in the siphon-type discharge passage was obvious poor compared with the scheme proposed by the contractor. Model tests were carried out respectively in the overseas and domestic and the model test results were basically consistent with those of numerical prediction, but the pumping system efficiency in high efficiency zone achieved in model tests was a litter lower than that by CFD. The optimized pumping system was characteristic of higher pumping efficiency and larger flow rate when operated at the designed conditions. The measuring results onsite shown that the best efficiency is more than 80% by use of the optimized pumping system installing mixed-flow pumps with guide vanes.

Development and Outlook for Self-priming Pumps

Background: Self-priming pumps are a type of general mechanical equipment that is widely used in the petroleum, chemical, electric power, metallurgy, mining, shipbuilding, light industry, agriculture, civil defense, and other departments, and they play an important role in the global economy. The pump system is the most common piece of equipment that consumes the most electricity, and reducing the energy consumption of the pump will save a significant amount of energy. Objective: For the benefit of scholars and engineers, this paper summarizes the most recent research on self-priming pumps, analyzes their solutions to the problem of reducing energy consumption, and discusses their advantages and disadvantages. Methods: The typical self-priming pump patents are outlined below based on the many functions of the improved self-priming pump structure, including pump body protection, high efficiency, and energy savings, ease of movement, and improved seal. The current self-priming pump patents are used to examine the development trend for these pumps. Results: The fundamental issues with self-priming pumps are outlined and studied through comparisons of various types and functions, and a future course for their development is suggested. Conclusion: The development of self-priming pump technology benefits from the improvement of self-priming pump structure. A self-priming pump with a straightforward design, automation, high efficiency, and energy conservation has a promising future.

Model test and analyses for a mixed-flow pumping system in the S-to-N Water Diversion Project of China

Abstract Baoying Pumping Station as the first station built in the East Route of the S-to-N Water Diversion Project in China, due to the importance of water source project and its 5000 hours yearly operating time, a serial of model tests and other measures were taken to secure its safety and high efficiency operation. Through the comparative model tests in the preliminary design stage, it was made clear that mixed-flow pump was the right direction of pump selection. The acceptance model test indicated that all performance requirements were satisfied and the head-weighted efficiency of the pumping system reached 80.5%, which was about 7 percentages higher than that obtained in the preliminary research and a good foundation for its efficient and economical operation was laid. The optimization design of inlet and outlet flow passages was not significant for improve the efficiency of pumping system. The verification test results were very close to the acceptance test results, and have been confirmed each other. The international bidding and mechanism of joint venture in purchasing main equipment for Baoying pumping station proved to be a success in introducing advanced foreign technology, and its construction experience can provide a useful reference for similar pumping stations.

Frost-resistant embankments with a novel ground source heat pump system

This study introduces a novel artificial heating technique aimed at addressing frost heave issues in embankments on frozen ground, offering a sustainable solution. Initial evaluations assessed various heating systems, including boilers, heat pumps, solar heaters, and electric heaters, focusing on their thermal performance and applicability. The study subsequently designed and implemented a direct-expansion ground source heat pump (DX-GSHP) system as the primary heat source for embankment warming. Rigorous testing confirmed the DX-GSHP system's ability to maintain a heat-supply temperature above 40 °C and a heat-absorption temperature below −3.5 °C, effectively extracting geothermal energy for transfer to the topsoil layers. With a demonstrated coefficient of performance (COP) of 3.49, the DX-GSHP system not only proves its energy efficiency but also suggests a potential role in reducing the strain on electricity supply systems. Installation of DX-GSHPs, with heating capacities ranging from 1.0–2.0 kW and spaced at intervals of 2.0–4.0 m, provides a rapid thermal response to frost heave in single-track railway embankments, thereby potentially mitigating frost-induced damage in cold climate regions.

A method for estimating maximum safe installable power for groundwater extraction with application to Africa

New groundwater development is a likely way to meet growing global water demand but needs careful management. To help inform the sustainable development of groundwater resources, a novel method based on the maximum safe installable power for water pumping systems and the maximum safe remaining installable power (considering current abstraction) is developed. The proposed model couples energy, technology and hydrogeological parameters, and is then developed to compute the maximum power that can be safely installed per km2 without exceeding a maximum annual pumpable volume, calculated through available recharge and storage. The model is applied to estimate the maximum safe installable power across Africa with a 0.2-degree resolution, using available energy and hydrogeological data. Constrained by recharge (considering that 25 % of the annual recharge is available for utilization), the maximum safe installable power ranges between 0 and 9960 W/km2 across Africa with regions such as the Congo Basin (~340 W/km2), and western Africa between the Ivory Coast and Nigeria (~230 W/km2) identified as having high potential for sustainable pumping system development. Constrained by storage (considering that 0.1 % of storage can be withdrawn per year), it ranges between 0 and 13,425 W/km2 highlighting the ability to harness storage for pumping system development in the large aquifers of Northern Sahara (~8720 W/km2). When considering limitations posed by both groundwater recharge and aquifer storage (considering that 25 % of the annual recharge and 0.1 % of storage can be withdrawn per year), along with current groundwater withdrawal, 93 % of the maximum safe installable power remains still installable on average across Africa. Nevertheless, 2 % of the locations are estimated to be already experiencing overexploitation, particularly in Sudan, northern Africa, and northeastern South Africa. These findings provide a novel and adaptable way to examine water security, which can assist institutions in targeting investments to meet water demand sustainably.

Dynamically coupled modelling of ground source heat pump systems considering groundwater flow and unbalanced seasonal building thermal loads

The ground source heat pump (GSHP) system is a promising technology to exploit shallow geothermal energy via ground heat exchangers, GHEs (e.g., deep boreholes or piles) for space heating or cooling. Although GSHP systems have been widely used in temperate regions owing to their environmentally clean characteristics and excellent energy-saving performance, their use in cooling-dominated areas, such as subtropical or tropical regions (e.g., Hong Kong or Singapore), remains limited. The operation of GSHP systems in these regions may be subjected to unbalanced seasonal thermal loads on buildings and induce heat accumulation in soils surrounding GHEs, leading to potential deterioration in the long-term performance (e.g., coefficient of performance, COP) of GSHP systems. To properly evaluate the long-term COP of GSHP systems in cooling-dominated areas, a dynamically coupled simulation approach is proposed in this study. The proposed method integrates building thermal loads with ground heat transfer under groundwater seepage flow, within a unified framework. The effectiveness of this approach is demonstrated through a case study where, in the absence of groundwater seepage flow, the soil temperature increased by 17.2 °C. In contrast, when groundwater seepage flow was considered, the GSHP system not only maintained a high long-term cooling COP but also achieved up to 30 % electricity savings. These findings demonstrate the feasibility and sustainability of applying GSHP systems in cooling-dominated areas with the aid of groundwater seepage flow.

Optimized design of SynRM drive systems for high-efficiency solar water pumps

This study presents the design and implementation of a Synchronous Reluctance Motor (SynRM) with an integrated drive circuit for a 4-inch submersible pump motor, tailored for small-scale solar photovoltaic water pumping systems. The SynRM operates efficiently at low voltage levels, eliminating the need for a boost converter and allowing direct connection to low-voltage power sources. With a power output of 0.55 kW and an ultra-premium efficiency rating of 86.5%, the motor integrates the drive circuit within its casing for a compact design. It operates across a voltage range of 15 V to 95 V, using efficient buck converters for required output voltages. This paper discusses the design, optimization, and prototyping of the motor and drive circuit, highlighting innovative solutions for advancing small-scale solar-powered water pumping systems. Electric motors, especially pump motors, are major consumers of electrical energy. Enhancing their efficiency can significantly impact total energy consumption. This study's SynRM and integrated drive system, optimized for high efficiency, durability, and cost-effectiveness, can be directly powered by PV panels, offering a compact and efficient alternative to traditional systems.

Coordination of energy loss and fish friendliness for a low-head tubular-pump blade based on a multi-objective optimization model

Tubular pumps and turbines are the water-to-electricity conversion devices widely used in pumped hydro storage systems for low heads and high flow rates. An ecological concern is the high proportion of fish injuries caused by the rotating blades. In this study, a tubular pump blade is retrofitted to balance the energy loss and fish friendliness through multi-objective optimization, combining computational fluid dynamics with a mathematical blade strike model. Sensitivity analysis identifies nine geometric variables out of thirteen for optimizing blade design. An approximation model is developed to implement optimization algorithm and achieve the objective function. By artificially assigning weights to targeted performance metrics, three scenarios are obtained: the optimal efficiency scheme (A), the optimal fish friendliness scheme (C) and the balanced scheme (B). Scheme C achieves a fish survival ratio of 100 % at multiple flow rates (for fish lengths of Lf/D=1/12), but results in a 6.4 % decrease in efficiency compared to scheme A. Additionally, a negative blade attack angle can improve flow pattern. Considerable reduction in fish mortality can be obtained by equipping the rotor with a larger size but lower shaft speed, while also limiting the fish size to pass through the pump running at a reduced flow rate.

Selection of refrigerant based on multi-objective decision analysis for different waste heat recovery schemes

Waste heat generation, upgrading, and refrigeration are the fundamental ways to recover and utilize waste heat. The rationalizing the use of refrigerants also contribute in creating energy savings and minimizing carbon emissions. This study evaluated the thermodynamics, economics, and environmental of different types of refrigerants in three kinds of waste heat recovery schemes: generate electricity, heat pump, and refrigeration. Based on this, the entropy weight and Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) were combined to assess the overall performance of the refrigerants. A thorough analysis revealed that R1234ze(E) can replace R245fa and R123 in the organic rankine cycle (ORC). The best refrigerant for vapor compression refrigeration (VCR) and high temperature heat pump (HTHP) systems is R1243zf. In addition, the multi-objective decision analysis shows that the performance difference among the nine selected refrigerants is the total cost, followed by the environmental impact. The approach is successful in recognizing the variations between different refrigerants in the same waste heat recovery scheme and gives a thorough evaluation. It sets instructions for the future use of eco-friendly refrigerants and their application waste heat recovery schemes.

Assessing the impacts of air-sealing on the sizing, operation, and economic feasibility of ground-source heat pumps for electrifying single-family houses in the US

According to recent studies and reports, in single-family houses (SFHs), air-sealing can significantly lower the thermal loads for space heating and cooling. Thus, air-sealing in SFHs could reduce the required size and cost of ground source heat pump (GSHP) systems for electrifying SFHs. This study investigated the costs and benefits of integrating air-sealing with GSHPs for retrofitting existing SFHs when compared with air-source heat pumps. A whole building energy simulation tool integrated with an advanced design tool for modeling ground heat exchangers was used to calculate changes in required GSHP capacity, total borehole length, and building energy consumption with and without air-sealing in SFHs in 16 US climatic regions. The results from this study showed that reducing outdoor air infiltration from 0.8 air changes per hour (ACH) to the minimum ventilation requirement (0.35 ACH) can significantly reduce borehole length (up to 55%), GSHP capacity (up to 48%), and total heating electricity reduction, especially in cold climates (up to 44%). The results also showed that for airtight homes (0.03 ACH infiltration) with a direct outdoor air system, the minimum required borehole length, GSHP capacity, and total heating electricity consumption can be reduced up to 70%, 68%, and 67%, respectively, when compared with SFHs with 0.8 ACH infiltration. Moreover, the life cycle cost analysis showed that air-sealing in conjunction with a GSHP is more profitable than replacing the existing system with an air-source heat pump, even without any incentives for most climatic regions in the US (except for some hot regions).

Experimental comparison of First-law analysis of peak hour operation of GSHP system under optimized conditions

The present study presents a novel procedure to study energy – efficient performance of a Ground − Source Heat Pump (GSHP) system during peak hour space cooling and heating operations by integrating an experimental study with First law analysis and optimization techniques. The main objective of the study is to identify how closely the results of First law analysis agree with the actual experimental results when operated under optimized conditions. The experimental data obtained during peak hour operation of a 17.58 kW GSHP system for each three days of operation in summer and winter seasons are considered for the analysis. The Coefficient of Performance (COP) and Power Consumption (W) of the GSHP system are computed using an energy balance based on First law using the experimentally measured heat rejection by the Borehole Heat Exchangers (BHEs) and the cooling effect. For optimization using the Taguchi method, six distinct measured parameters, each at three different levels, are selected as variables. Analysis of Variance (ANOVA) was carried out on COP and W to ascertain the parameters that exert the most significant influence on the performance of the GSHP system. During peak hour operation, the temperature difference between the inlet and outlet water in the BHE was found to be 10–11 °C in cooling mode and 3 °C to 4 °C in heating mode operations. Temperatures of water in the BHEs and air at the heat pump, which contribute to the heat interaction, are found to be the most influential parameters for cooling and heating mode operations. The COP for cooling mode computed by the optimization technique, 3.59, closely agrees with the experimental COP of 3.73. Similarly, the optimized COP for heating mode, 3.84 is found to be closer to the experimental COP of 4.32. The optimized power consumption deviates by 14.21 % and 11.94 % from the experimental results for cooling and heating modes, respectively.

Water heater storage heat pump cycle for higher operating range

Heat pumps for water heating have become increasingly attractive. However, the achievable water temperature using a vapor compression heat pump water heater (HPWH) is often constrained by the compressor operating envelope. To address this challenge, HPWHs typically employ two-stage compression with complex system architecture or rely on back-up electric heating. This work introduces an alternate storage heat pump concept to improve the operating temperature range of an R134a HPWH system. The developed system operates in two modes: Mode I functions as a typical wrap-around condenser HPWH, while Mode II splits the wrap-around coil to use the top portion as a condenser and the bottom portion as evaporator. System modeling consisting of a vapor compression cycle and water tank sub-models was conducted to study the performance. The model was validated experimentally. The storage heat pump system could achieve an additional increase of 12 °C beyond the maximum possible water temperature of 46 °C which was achieved using the baseline conventional HPWH system. In Mode II, the system exhibits a 20 % higher average heating capacity and a 15 % lower average pressure ratio compared to the conventional system operating at a 27 °C ambient temperature. Compared to usage of electric heating elements, our system showed a longer recovery time with a 50 % lower energy consumption for a similar increase in water temperature.

Three-dimensional analysis of multiple inclined borehole heat exchangers

This research develops and applies a numerical modelling method for inclined borehole heat exchangers (BHE) in ground-source heat pump systems. Inclined BHEs have the advantage of reducing the ground-level footprint of the overall BHE field. Computational modelling of the ground heat transfer using the commercial code COMSOL Multiphysics has revealed that inclined BHEs offer additional performance benefits compared to vertical BHE fields. When heat is injected constantly, both types of fields perform similarly at first, but over a longer period of time, the inclined BHE fields show significant benefits due to the increased ground volume in the deeper portion of the field. Similar conclusions are reached when transient loading conditions are considered. Notably, when cooling dominates, inclined BHE fields outperform vertical ones for a simulated period of 10 years. This indicates that inclined BHE fields are better equipped to handle imbalanced energy loads. To summarize, inclined BHE fields offer advantages in ground-volume utilization and resilience to energy load imbalances compared to vertical fields.

Environmental, economic, and eco-efficiency assessment of residential heating systems for low-rise buildings

Transitioning from fossil fuels to renewable heating is essential for rapidly reducing greenhouse gas emissions. Besides greenhouse gas emissions, other environmental and economic impacts are crucial for successfully implementing renewable heating systems. This study evaluates 13 residential heating systems' environmental, economic, and eco-efficiency performance for a typical German two-story dwelling. The life cycle assessment method is employed to quantify the environmental impacts. Assuming a sustainable supply of biomass-based fuels, biomass heating systems exhibit the lowest environmental impacts, whereas gas heating systems are associated with high environmental impacts. Among heat pump systems, the water-source heat pump demonstrates the lowest environmental impact. Additionally, integrating a PV system into heat pump systems reduces the environmental impacts across all heat pumps. The evaluation indicates that the air-source heat pump is the most economical system, while the pellet boiler with solar thermal support and the heat pump with ice storage incur the highest costs. However, the cost differences among the heating systems are relatively small, making it challenging to establish a clear ranking based solely on economic evaluation. An eco-efficiency assessment, which combines environmental and economic aspects into a single indicator, reveals that the most eco-efficient systems are the air-source heat pump, both with and without a PV system, and the wood gasifier heating system. In contrast, the ice-storage heat pump and the pellet heating with solar thermal support show the lowest eco-efficiency.

Efficient waste heat utilization in high-temperature proton exchange membrane fuel cell bus through integration of lithium bromide absorption refrigeration

Compression-type air-conditioning heat pump systems used in high-temperature proton exchange membrane fuel cell (HT-PEMFC) buses significantly increase the vehicle's hydrogen consumption. This study introduces a lithium bromide (LiBr) absorption refrigeration air-conditioning system into a fuel cell bus, aiming to convert the high-quality waste heat produced by the HT-PEMFC into cooling and heating capabilities for balancing the temperature within the vehicle cabin and recover waste heat. Modeling and co-simulation of the HT-PEMFC, LiBr absorption refrigeration system, vehicle thermal model, and compression-type air-conditioning heat pump system were conducted using MATLAB/Simulink. The simulation results indicate that, compared with the traditional compression-type air-conditioning heat pump system, the LiBr absorption refrigeration system can save 6.13–18.17 % of hydrogen and improve the electrical energy and exergy efficiencies by 3.58–10.74 % and 3.74–11.22 %, respectively, under different driving scenarios. Using the LiBr absorption refrigeration system significantly enhances the vehicle's overall fuel utilization efficiency and driving range.

Application of PVT Coupled Solar Heat Pump System in the Renovation of Existing Campus Buildings

A photovoltaic thermal panel (PV/T) is an integrated module that harnesses both photovoltaic and solar thermal technologies to convert solar energy into electricity and heat, thereby enhancing overall energy efficiency. This paper aims to explore the suitability of PV/T solar heat pump systems across various climate zones and assess their potential for widespread application. By analyzing the operating principles of an indirect expansion PV/T solar heat pump system in conjunction with the climate characteristics of different regions, MATLAB R2019b/Simulink software was employed to evaluate the photoelectric performance of PV and PV/T systems in representative cities across five distinct climate zones in China during typical winter days. Key metrics, such as power generation, hot water storage tank temperature, indoor temperature, and system COP, were chosen to assess the heating performance of the PV/T solar heat pump system. The findings indicate that the winter ambient temperature significantly affects the photoelectric efficiency of both the PV and PV/T systems. While higher latitudes with lower ambient temperatures yield greater photoelectric efficiency, the southern regions exhibit higher power generation during winter. The winter heating effectiveness of the PV/T solar heat pump system is mainly influenced by indoor and water tank temperatures, with Harbin’s system performing the poorest and failing to meet heating demands, whereas Nanjing’s system shows the best results.

Multilayer decoupling control of photovoltaic integrated heat pump based on expected value

Abstract In this paper, a multilayer decoupling control method for photovoltaic heat pumps based on expected values is proposed, which aims to achieve the optimal operation of the photovoltaic heat pump system and photovoltaic heat pump system. This method predicts the output energy of photovoltaic photovoltaic system and realizes multilayer decoupling control based on the load demand of the heat pump system. In order to adapt to the change in environment, the adaptive fuzzy PID compound control method is adopted to optimize the control strategy. Experimental results show that this method can effectively improve the system efficiency, reduce energy consumption, and demonstrate good adaptability and stability.