Search Results (9)

Due to the hot climate, energy consumption for refrigeration is significantly higher in the subtropical monsoon climate region. Combined with renewable energy and ice-storage technology, a model predictive control model of the regional cooling system was proposed, which was conducive to improving the flexibility of the regional cooling system and the ability of peak shifting and valley filling. In this model, an artificial bee colony (ABC) optimized back propagation (BP) neural network was used to predict the cooling load of the regional cooling system, and the model parameter identification method was adopted, combining utilizing a river-water-source heat pump and ice-storage technology. The results showed that the load prediction algorithm of the ABC-BP neural network had a high accuracy, and the variance coefficient of load prediction root-mean-square error (RMSE) was 16.67%, which was lower than BP, support vector regression (SVR), and long short-term memory (LSTM). In addition, compared with the three control strategies of chiller priority, ice-storage priority, and fixed proportion, the operation strategy optimized by the comprehensive model can reduce the average daily cost by 19.20%, 4.45%, and 5.10%, respectively, and the maximum daily energy consumption by 30.02%, 18.08%, and 8.90%, respectively. Full article

The discharge of warm water from water source heat pump (WSHP) energy stations can cause local changes in the water temperature, leading to changes in the water quality around and downstream of the discharge outlet, resulting in a cumulative effect that alters the aquatic habitat elements and affects the ecosystem stability. This study took the demonstration project of the water source heat pump energy station in the Hankou Binjiang International Business District of Wuhan City as an example. Based on measured data, this study established the control equation for the warm water discharge of the project and used FLUENT 2022 R1 software to establish a numerical model of warm water diffusion. This study analyzed the changes in discharge water temperature during unfavorable conditions in both summer and winter during dry and wet seasons by using four parameters: equal area surface, volume, length, and width of the area of influence. The results suggest that the impact of the project’s warm water discharge on the temperature of the river body will quickly decay and its impact range will be limited. Hence, the project will not have adverse effects on the water and ecological environment in the mid–lower reaches of the Yangtze River. Full article

In the context of carbon neutrality, making full use of renewable energy is the key to further improve China’s development index. Within China’s Yangtze River Economic Belt, solar energy and river water, as clean and abundant sources of renewable energy, have garnered increasing. In this paper, a solar energy and surface water driven cogeneration system model is developed by TRNSYS to provide users with heat, cold and electricity. Six representative cities located along the upper, middle, and lower reaches of the Yangtze River Economic Belt were selected to evaluate and analyze the energy-saving, emission reducing, and economic and environmental benefits of solar energy and river water heat utilization in the aspects of energy, economy, and environment. The results shows that the annual power output of PV/T-GSHP system, from the west to the east of the Yangtze River, shows a phase growth trend, which is related to the light intensity. The annual heat output of PV/T plate gradually decreases from the lower reaches of the Yangtze River to the upper reaches. The research findings confirm the application potential of new energy sources in the Yangtze River Economic Belt and quantify the emission reduction effects of new environmental protection actions such as solar energy and river water heat sources. It provides valuable guidance for the utilization of new energy sources, including solar energy and surface water heat energy in the Yangtze River Economic Belt, as well as for optimizing energy policies. Full article

Issues of energy efficiency and sustainability in buildings are gaining increasing attention in the context of the “3060” dual-carbon initiative. In recent years, nearly zero-energy buildings (nZEBs) have emerged as a potentially viable solution to the challenges of the energy crisis in the building sector, and it is important to study the factors influencing their energy consumption and carbon emissions. However, existing research lacks analyses of multifactor interactions, and the problem of high energy consumption has not been sufficiently addressed. Taking a typical residential building in the Yangtze River basin as the study subject, this study, jointly funded by the University of Nottingham and Hubei University of Technology, proposes a hybrid approach that combines building energy simulation and orthogonal experiments to investigate factors pertaining to buildings, people, and the environment to identify key influencing factors and explore the energy consumption and carbon emission characteristics of residential buildings in hot summer and cold winter (HSCW) zones. Our findings reveal the following: (1) The use of renewable energy sources, such as solar photovoltaic power generation and solar hot water, and renewable energy systems such as ground-source heat pumps, in the operation phase of a baseline building can result in a 61.76% energy-saving and a 71% renewable energy utilization rate. (2) To more easily meet the requirements of nZEB standards, it is recommended to keep K_E within the range of 0.20–0.30 W/(m²·K), K_R within the range of 0.15–0.20 W/(m²·K), and VT within the range of 0.6–0.7 h⁻¹. This study will help to identify the critical factors affecting energy consumption and provide a valuable reference for building energy efficiency in HSCW zones. Full article

This study aims to institutionalize an evaluation methodology to assess water-source heat pumps (WSHPs) when designing a zero-energy building. Thus, regions where zero-energy buildings were designed were subdivided into 66 sub-regions, thereby standardizing the temperatures on the source side of WSHPs using river water and pipeline water. Based on these data, ground-source and water-source heat pump system-based simulation (new and renewable energy self-sufficiency rate compared to building energy consumption) values were derived for cases whose condition (region or heat source) was different among the buildings certified as zero-energy buildings. The application of the standard meteorological data and reference hydrothermal data to the ECO2 program and outcome evaluation led to the following findings: in all cases (reference: Seoul), ground-source heat pumps (GSHPs) showed a higher self-sufficiency rate than WSHPs (ground source > pipeline water > river water). The self-sufficiency rate of GSHPs was 11–33% higher than that of WSHPs. In a regional comparison among the cold (Jeongseon), central (Seoul), and southern (Jeju Island) regions, WSHPs exhibited higher energy self-sufficiency rates than GSHPs under the conditions of higher water temperatures in winter and lower water temperatures in summer, as in the southern region. Full article

River water source heat pump (RWSHP) systems are being proposed to reduce the energy consumption and carbon emissions of buildings. The RWSHP system is actively applied to large-scale buildings due to its stable performance. The application of RWSHP in large-scale facilities requires an accurate capacity design with considerations of building load, heat source, and environment conditions. However, most RWSHP systems are over-designed based on peak load of buildings. These design methods, based on peak loads, are economically and environmentally disadvantageous. Therefore, this paper aims to development an optimal design method, both economically and environmentally, for the RWSHP system. To develop this optimal design method, a simulation model was created with an optimization algorithm. The economics of the RWSHP system were calculated bases on present worth of annuity factor. Moreover, CO₂ emissions were estimated using the life cycle climate performance proposed by the International Institute of Refrigeration. The total cost of the proposed RWSHP system that apply the optimum design method decreased by 24% compared to conventional RWSHP systems. Moreover, CO₂ emissions of the proposed RWSHP system reduced by 4% compared to conventional RWSHP systems. Full article

Seasonal variations of water temperature, electric conductivity, and oxygen isotope and chemical composition of shallow groundwaters and river waters were determined in the Sho River alluvial fan, western Toyama Prefecture, Japan, to examine groundwater heat utilization for indoor climate control. Samples were collected at 31 sites every 2 months for 1 year and at 11 representative sites monthly. In addition, the results of monthly precipitation amount and oxygen isotope composition of precipitation collected within the region during the same period were also taken into account. The sources of the shallow groundwaters are a mixture of river water and precipitation. The contribution of precipitation to groundwater is generally small along the Sho River but reaches as much as 80% along the Oyabe River and in the south and west of the alluvial fan. Though the origin of the groundwater differs regionally, water temperature is fixed at around 15 °C throughout the year in the northern part of the alluvial fan, and open-type ground source heat pump systems can be used for cooling and heating there, if adequate quantitative aquifer properties (exploitable groundwater amounts) are present. Full article

Temperature differences between the atmosphere and river water allow rivers to be used as a hydrothermal energy source. River-water heat pump systems are a relatively non-invasive renewable energy source; however, effluent discharged from the heat pump can cause downstream temperature changes which may impact sensitive fluvial ecosystems. The temperature change associated with heat pump discharge in a river reach was examined using the heat transfer equation in a previous study, but not using models. There were also no studies on the impact of temperature change due to heat pump discharge on river ecosystem elements such as endangered fishes. Therefore, in this study, the water temperature recovery distance of effluent was estimated for a river section in the Han River Basin, Korea, using the heat transfer equation and the Environmental Fluid Dynamic Code (EFDC) model. The water temperature recovery distance was estimated to be 9.7 km using the heat transfer equation and 5 km using the EFDC model in summer. It was also estimated to be 4.5 km using the heat transfer equation and 6.7 km using the EFDC model in winter. Results showed that the water temperature recovery distance results estimated by the heat transfer equation had greater variation than the EFDC model. The water temperature recovery distance could also be used as an objective indicator to decide the reuse of downstream river water. Furthermore, as the river system was found to support an endangered fish species that is sensitive to water environment changes, care should be taken to exclude the habitats of protected species affected by water temperatures within water temperature recovery distance. Full article

This paper studies the long-term performance of a Ground Source Heat Pump (GSHP) system and a Water Source Heat Pump (WSHP) system for an office building in Suzhou, which is a hot summer and cold winter climate region of China. The hot summer and cold winter region is the most urbanized region of China and has subtropical monsoon climate, therefore, Heating, Ventilation, and Air Conditioning (HVAC) systems are in great demand. Due to the fact that 42.5% of Suzhou’s total area is covered by lakes and rivers, the city has an abundance of surface water resources. Based on Suzhou’s meteorological data and the thermal characteristics of the building envelope, an office building model was created and the dynamic cooling and heating load was calculated using Transient System Simulation (TRNSYS) simulation software. Two numerical HVAC modeling systems were created: a GSHP system for which the data of an in-situ Thermal Response Test (TRT) was used and a WSHP system for which the Tai Lake water temperature was used. Simulating the performance of both systems over a 20-year period, the two systems were analyzed for their Coefficient of Performance (COP), heat source temperature variation, and energy consumption. The results show that the GSHP system causes ground heat accumulation, which reduces the system’s COP and increases energy consumption. The study also revealed that compared with the GSHP system, the WSHP system has a more stable long-term performance for buildings in Suzhou. Full article