Hybrid Heating System Research Articles

Optimal operating strategy of hybrid heat pump − boiler systems with photovoltaics and battery storage

The growing need to reduce energy consumption and greenhouse gas emissions is driving the search for more efficient heating solutions in buildings. Hybrid heating systems, which combine air-to-water heat pumps (AWHP) with traditional gas boilers, are a common solution after refurbishment investments. However, managing these systems effectively, particularly when integrated with photovoltaic (PV) panels and battery energy storage systems (BESS), remains a complex task. For instance, heat pumps perform poorly in very cold conditions, making boilers a more efficient option; however, it might be advantageous to use it to increase electricity self-consumption. Optimal management depends on multiple factors, including future forecast data. In this paper, a daily optimization program is developed by means of a brute-force approach using forecast data. The core innovation of this paper is the use of an artificial neural network (ANN) that, trained on predictive optimization results, can determine the optimal solution in real-time without the need for future forecasts. The ANN achieved a 99.16% accuracy in new scenarios, successfully optimizing costs, CO2 emissions, and primary energy use. Results indicate up to 19% cost savings in colder cities, a 12% reduction in CO2 emissions, and a 3% decrease in primary energy consumption. This approach holds significant potential for enhancing the integration of renewable energy sources, contributing to long-term sustainability goals.

Research on Hybrid Heating System in Cold Oilfield Regions

Efficient and clean treatment of wastewater and energy recovery and utilization are important links to realize low-carbon development of oilfields. Therefore, this paper innovatively proposes a multi-energy complementary co-production heating system which fully and efficiently utilizes solar energy resources, oilfield waste heat resources, and biomass resources. At the same time, a typical dormitory building in the oil region was selected as the research object, the system equipment selection was calculated according to the relevant design specifications. On this basis, the simulation system model is established, and the evaluation index and operation control strategy suitable for the system are proposed. The energy utilization rate of the system and the economic, energy-saving, and environmental benefits of the system are simulated. The results show that, under the simulated conditions of two typical days and a heating season, the main heat load of the system is borne by the sewage source heat pump, the energy efficiency is relatively low in the cold period, and the energy-saving characteristics are not obvious. With the increase in heating temperature and anaerobic reactor volume, the energy consumption of the system also increases, and the energy efficiency ratio of each subsystem and the comprehensive energy efficiency ratio of the system gradually decrease. In addition, although the initial investment in cogeneration heating systems is high, the operating costs and environmental benefits are huge. Under the condition of maintaining 35 °C, the anaerobic reactor in the system can reduce carbon emissions by 12.15 t per year, reduce sulfur dioxide emissions by 98.4 kg, reduce dust emissions by 49.2 kg, and treat up to 2700 t of sewage per year, which has broad application prospects.

Demand Response Potential of an Educational Building Heated by a Hybrid Ground Source Heat Pump System

Demand response (DR) enhances building energy flexibility, but its application in hybrid heating systems with dynamic pricings remains underexplored. This study applied DR via heating setpoint adjustments based on dynamic electricity and district heating (DH) prices to a building heated by a hybrid ground source heat pump (GSHP) system coupled to a DH network. A cost-effective control was implemented to optimize the usage of GSHP and DH with power limitations. Additionally, four DR control algorithms, including two single-price algorithms based on electricity and DH prices and two dual-price algorithms using minimum heating price and price signal summation methods, were tested for space heating under different marginal values. The impact of DR on ventilation heating was also evaluated. The results showed that applying the proposed DR algorithms to space heating improved electricity and DH flexibilities without compromising indoor comfort. A higher marginal value reduced the energy flexibility but increased cost savings. The dual price DR control algorithm using the price signal summation method achieved the highest cost savings. When combined with a cost-effective control strategy and power limitations, it reduced annual energy costs by up to 10.8%. However, applying the same DR to both space and ventilation heating reduced cost savings and significantly increased discomfort time.

Design and performance evaluation of a solar-assisted biogas and air-source heat pump hybrid system for radiant heating applications

Energy and environmental crises have become critical challenges, making the efficient use of clean energy a focus of public attention. Although emerging clean energies have high economic and environmental values, these single energy sources are not well-developed. In colder climates, maintaining a stable fermentation temperature can be difficult, leading to the idling of many biogas digesters. Furthermore, despite extensive research on solar-assisted air-source heat pumps, these systems perform poorly in cold climates with low solar irradiance. To address these issues, this study investigates the integration of a solar-assisted biogas and air-source heat pump hybrid heating system (SBHP-HHS) for capillary radiant heating in rural North China, specifically adapted to local conditions. The system aims to utilize the combined benefits of various clean energy sources to improve system reliability in harsh climates. By combining experimental analysis with TRNSYS simulation, the system performance during the heating season in rural northern China was evaluated. Experimental results show that the hybrid system, utilizing the radiant capillary terminal, is capable of maintaining room temperatures above 20 °C, demonstrating its effectiveness. Simulation results show that the air-source heat pump achieves a coefficient of performance (COP) of 4.6. This efficiency level is generally favorable, ensuring stable operation. Additionally, the system achieves a solar-biogas hybrid utilization rate exceeding 75 % and a primary energy-saving rate of 78 %. Economically, the system offers an 8.23-year dynamic payback period and annual cost savings of 3055 CNY. Environmentally, it reduces CO2 emissions by 4263.6 kg annually. This study provides a solid experimental foundation for further research, offering empirical evidence to optimize system performance.

A comprehensive review of the hybrid heating systems consisting of heat pumps and solar collectors for hot water and space heating application

A comprehensive review of the hybrid heating systems consisting of heat pumps and solar collectors for hot water and space heating application

Solar-assisted biogas system with air-source heat pump for the energy-saving of indoor heating in north China

Abstract To address the challenges associated with winter heating in high-latitude regions of China, solar-assisted biogas heating systems have emerged as the predominant focus of research due to their cost-effectiveness, accessibility, and environmentally friendly attributes. However, traditional solar-assisted biogas heating systems encounter issues of low efficiency and limited practicality resulting from unstable solar radiation and extreme ambient temperatures during the heating season. To improve the economy and stability of the system, this study proposed a novel operational control method for a small-scale energy station system in rural regions of North China, named Solar-Biomass-Air Source Heat Pump Hybrid Heating System (SBHP-HHS). The integration of solar energy, biogas energy, and air-source heat pump (ASHP) systems in this proposed work has shown to create effective complementarity and enhances the production efficiency of the existing system. Test and simulation studies have been carried out for this system. The layout of buildings and equipment within a university campus in Beijing is reconfigured and redesigned, incorporating an ASHP into the existing heat source configuration. To begin with, a mathematical model is established for the complementary heating system that incorporates solar energy, a biogas digester, and an ASHP. Subsequently, a dynamic simulation model is developed using the TRNSYS platform, and a corresponding operational control strategy for the multi-energy complementary heating system is proposed. Dynamic simulation and analysis of the newly implemented system are performed using the TRNSYS platform, focusing on energy flow and thermodynamic performance. Throughout the heating season, the solar-biogas integrated system achieves a remarkable assurance rate of up to 79%. Additionally, ASHP maintains a relatively high heating efficiency, coefficient of performance (COP) reaches 3.02. Finally, an economic evaluation of the multi-energy complementary system was conducted based on the annual cost method. This was compared with the clean approach of using only an ASHP unit. The results indicate that the SBHP-HHS is more economical when the anticipated useful life is 6 years or longer. The results indicate that the proposed can achieve significant energy-saving and carbon-reduction benefits in rural areas, catering to their heating needs.

Optimization of solar-air source heat pump hybrid heating system

Abstract In order to construct a versatile, complementary, low-carbon, clean, and efficient heating system, this study explores the potential of a solar-air source heat pump (SAHP) hybrid heating system. A simulation model is established in TRNSYS, and the particle swarm algorithm (PSO) and genetic algorithm (GA) from GENOPT and MATLAB are employed. With the aim of minimizing the annual cost, optimization is conducted on the key parameters and operational strategies of the system. Comparative analysis between the two algorithms reveals that PSO slightly outperforms in cost reduction, while GA exhibits a slight advantage in enhancing system performance. Significantly improved energy savings are achieved by appropriately reducing the rated heating capacity of the air source heat pump and increasing the volume of the water tank.

Analysis of the Hybrid Power-Heating System in a Single-Family Building, along with Ecological Aspects of the Operation

This study evaluates a hybrid heating system in a single-family building in northeastern Poland, which has a temperate continental climate. The analysis covers two heating seasons in 2021/2022 and 2022/2023. The hybrid heating system includes an air heat pump HPA–08 CS Plus with a heating power of 8.2 kW (AHP), a condensing gas boiler VC146/5–5 with a power of 14 kW (GB–Condens.), and a solid fuel boiler with a power of 11 kW for central heating. Additionally, hot water is heated by a Basic 270 (DHW’s AHP) air–water heat pump with a power of 2 kW, utilizing a tank with a capacity of 270 dm3 equipped with two heating coils. The building’s average electricity consumption is around 5400 kWh/year. A 4.96 kWp photovoltaic installation is installed on the building’s roof at a 40° angle towards the south to supplement the hybrid system. The study aims to assess whether the PV installation can adequately cover the energy needs of the hybrid heat source for heating and hot water. Furthermore, the study calculates the emission of pollutants (CO2, SOx, NOx, CO, and PM10) into the atmosphere. The total annual electricity production from PV installations was 5444.9 kWh in 2021/2022 and 5684.8 kWh in 2022/2023. The excess electricity was stored in the PGE power grid as per the Prosumer settlement rules. The installed PV installation is sufficient to power the following devices annually: AHP, DHW’s AHP, and GB–Condens. However, the daily electricity production from the PV installation is not enough to cover the energy needs of the heat pump for heating during the cold months in Poland (I–III, XI–XII). It can meet the power needs of a PC all year round and can also be stored during the summer months, for example, in energy warehouses or by directly storing it in the PGE power grid. The use of the PV installation resulted in an average reduction in pollutant emissions into the atmosphere: CO2—94.1%, SOx—91.8%, NOx—95.6%, CO—9.7%, and PM10—32.1%.

Optimizing Hybrid Heating Systems: Identifying Ideal Stations and Conducting Economic Analysis Heating Houses in Jordan

Optimizing Hybrid Heating Systems: Identifying Ideal Stations and Conducting Economic Analysis Heating Houses in Jordan

Experimental research of photovoltaic-valley power hybrid heating system with phase change material thermal storage

The widespread integration of high-ratio distributed photovoltaic (PV) systems in buildings calls for flexible load management to align with municipal power peaks and PV variability. To address the timing and demand mismatches between PV generation and building energy needs, energy storage systems are used to manage PV excess, aid in grid peak shaving, and support building heating. This research develops a Photovoltaic-Valley power complementary phase change energy storage heating system, designed to consume photovoltaic and valley power for the decentralized heating of individual rooms, thus optimizing distributed energy utilization. A CPCM of magnesium chloride hexahydrate, EG, and calcium hydroxide, designed for indoor heating, was created with a phase change temperature around 117.9 °C and an enthalpy of 106.2 kJ/kg. An experimental platform was established to test the system and its control strategy, showing that the PV-powered phase change energy storage heater effectively keeps indoor temperatures above the thermal comfort minimum of 18 °C. As the PV guarantee rate increases, the system improves indoor temperature regulation and significantly reduces fluctuations. Operating costs are over 30% lower than those of traditional heating networks and natural gas systems, underscoring substantial energy savings and emission reductions. This research provides an integrated approach for optimizing building PV consumption, managing grid peaks, and regulating indoor temperatures with phase change energy storage heating systems.

Identifying hybrid heating systems in the residential sector from smart meter data

In this paper, we identify hybrid heating systems on a single residential customer’s premises using smart meter data. A comprehensive methodology is developed at a generic level for residential sector buildings to identify the type of primary and support heating systems. The methodology includes the use of unsupervised and supervised learning algorithms both separately and combined. It is applied to two datasets that vary in size, quality of data, and availability and reliability of background information. The datasets contain hourly electricity consumption profiles of residential customers together with the outdoor temperature. The validation metrics for the developed algorithms are elaborated to provide a probabilistic evaluation of the model. The results show that it is possible to identify the types of both primary and support heating systems in the form of probability of having electric- or non-electric type of heating. The results obtained help estimate the flexibility domain of the residential building sector and thereby generate a high value for the energy system as a whole.

Distributed multi-heat-source hybrid heating system based on waste heat recovery for electric vehicles

Air-conditioners usually consume the most electricity among all of the auxiliary components in an electric bus, over 30% of the battery power at maximum. A distributed multi-heat-source phased control method was developed to reduce the energy consumption of heating in electric vehicles (EVs). This method combines the application of multiple heat sources, including waste heat from battery cooling, motor and controller cooling, and positive temperature coefficient heating. Analyzed the internal thermal process and heat generation law of the power battery, and explored the thermal process of the driving motor and its controller. Apply the cooling waste heat from the power battery and the driving motor to the heating system of pure electric vehicles. The heat sources are distributed at different locations on the vehicle and provide heating in stages at various temperatures. Numerical analysis was conducted to calculate the heat output of each heat source, and a phased control strategy for the air conditioning system was designed according to the heat release characteristics and magnitudes of each component. Heating control functions for different stages were established at varying temperatures. The temperature rise patterns at different points on the vehicle were examined, and the positions of the heat sources were redesigned accordingly. The proposed method selects the appropriate heating mode according to factors such as the external temperature, the heat release sequence of the heating components, and passenger comfort requirements. Low-temperature experiments were performed at different temperature stages to compare the heating performance of this method with those of traditional heating methods and heat pump air conditioning for new energy vehicles. The experimental results show that the heating system has good heating effect. Compared with heat pump air conditioning and PTC heating, the proposed collaborative system saved 31.1% and 63.6% of energy, respectively, after operating at − 22℃ for 2 h. It demonstrates good energy-saving and heating performances at different temperature stages. The heating method is currently one of the best energy-saving solutions for EVs.

Public perceptions of heat decarbonization in Great Britain

AbstractHeating contributes significant carbon emissions, especially in countries that rely heavily on natural gas as in the UK. Switching to low‐carbon heating is imperative for reaching international climate change targets. Understanding public perceptions and acceptance of low‐carbon heating systems is a crucial part of the successful rollout of alternatives. This review examines public perceptions of different low‐carbon heating technologies, namely heat pumps, hydrogen boilers, hybrid heating systems, and district heating, as well as social factors such as heat experiences. The review focuses on the UK as a case study, which is characterized by high reliance on natural gas for heating with little progress to decarbonize this sector to date. The next years will be critical regarding decision‐making on what low‐carbon heating technologies to pursue. The review shows there is generally low awareness amongst the general public of the need to decarbonize heating and of the low‐carbon heating alternatives. A number of factors have been identified as playing a crucial role in influencing public perceptions of all low‐carbon heating systems, such as installation and running cost, thermal comfort, disruption, level of control, and environmental benefits. However, the acceptance of a new heating system is not simply the sum of several factors, as people's priorities vary across different contexts and technologies. Further public engagement on low‐carbon heating and support (e.g., financial) is necessary for increasing uptake. Future research could explore comparisons between the different low‐carbon heating technologies, key enabling factors, trade‐offs, and concrete policy support.This article is categorized under: Climate and Environment > Net Zero Planning and Decarbonization Policy and Economics > Energy Transitions Human and Social Dimensions > Social Acceptance

Solar-assisted hybrid oil heating system for heavy refinery products storage

The purpose of this study is to investigate the potential use of solar energy within an oil refinery to reduce its fossil fuel consumption and greenhouse gas emissions. A validated ASPEN HYSYS model was used to investigate the products produced from heavy crude oil in the refinery. Using TRNSYS software, the proposed Parabolic Trough Collector (PTC)-based solar heating system paired with the boiler is modelled. Sensible thermal energy storage (TES) system is integrated into the refinery's process heating to handle the intermittent nature of solar energy. It was discovered that 463 m2 of the PTC area coupled with a 15000-L TES tank can result in a maximum life cycle cost savings of 21.046 thousand USD for an annual heat supply of 116,944 MWh to generate steam at a temperature of 200–220 °C. In the proposed hybrid heating system, the yearly solar fraction is determined to be 26.99% and the payback period is 8.77 years with the average solar irradiance of 900 W/m2. In addition, the system can yearly reduce greenhouse gas (GHG) emissions by about 34.045 tonnes of CO2 equivalents.

Cost-optimization model to design and operate hybrid heating systems – Case study of district heating system with decentralized heat pumps in Finland

This paper introduces a novel optimization approach to design and operate hybrid heating system, which integrates existing centralized district heating assets and decentralized heat pumps. Hybrid heating system enables sector coupling, where electrified heating assets can provide ancillary services for the power market. A modelling tool to study the impact on total heat delivery costs of adding heat pumps into existing district heating based heating system was developed. The case study modelling results show that decentralized assets can support a primary side of district heating network and optimal use of heating assets decreases average operating expenditure by 24%. In order to capture the full value of hybrid heating system, one needs to be able to utilize heat pumps to provide ancillary services in power market and receive compensation for feeding heat pump heat into the district heating network. The modelling results are sensitive to various parameters. Hence, a thorough sensitivity analysis is presented for the results.

Uncertainty-based optimal energy retrofit methodology for building heat electrification with enhanced energy flexibility and climate adaptability

To reach net zero emissions by 2050, the UK government relies heavily on heat degasification in buildings by using heat pump technology. However, existing buildings may have terminal radiators that require a higher operating temperature than what heat pumps typically provide. Increasing the size of radiators and thermally insulating building envelopes could be a potential solution, but the feasibility of these practices is uncertain due to space constraints and high retrofit costs. This study investigates the feasibility and potential benefits of incorporating air-source heat pumps into existing gas boiler heating systems to meet heating demands. The proposed probabilistic optimal air-source heat pump design method enhances energy flexibility and climate adaptability, taking into account a wide range of uncertainty sources and multiple flexibility services (e.g., energy and ancillary services). Heating systems of three educational buildings at the University of Cambridge are used as a testbed to assess and validate the effectiveness of the proposed method, under future climate scenarios and projected decreases in heating demand due to climate change. Results indicate that the best retrofit alternative of the hybrid heating system reduces carbon emissions by 88%, total costs by 54% over its lifespan, and has an average payback period of around 3 years. Air-source heat pumps can meet the majority of the heating demand (around 80%) with gas boilers used for “top-up” heating during high demand. Furthermore, air-source heat pumps' design capacity can fulfil future cooling demand even if retrofit optimization is initially focused on meeting heating needs.

Prototype Design of Solar Collector Hybrid Heating System and Testing of Triethylene Glycol Nanofluid

The inclusion of solar energy, which is a renewable energy source, in heating systems in buildings provides significant advantages. To make heating with solar energy sufficient and efficient, nanofluids are used in solar collectors. In this study, a hybrid heating prototype is produced, a control mechanism controlling the operation of the hybrid system is established and tests are carried out by including monoethylene glycol, propylene glycol, aluminum oxide, copper oxide, titanium dioxide, especially triethylene glycol-based nanofluids in the system. Finally, a new nanofluid is obtained by mixing triethylene glycol with aluminum oxide and is tested on the prototype. With the tests carried out under the same conditions, the temperature differences of the nanofluids in a certain time period are observed and recorded. It is observed that the mixture of water and triethylene glycol provided the lowest temperature increase by providing a temperature increase of 8.6 °C in the range of 0-90 minutes. It also is observed that the highest temperature increase is achieved with the 21 °C temperature increase of the pure water and aluminum oxide mixture. Although the water and triethylene glycol mixture performs more inefficiently than other mixtures, it is thought that it can be used for heat storage since it heats up for a long time and cools down for a long time.

Thermal analysis of the hybrid HVAC unit using interpolant function

This study aims to cover the thermodynamic aspect of a geothermal site using the Hermite interpolant. The energy distribution, determination of the system exergy and the energy ratio are some of the factors investigated thoroughly. The steady flow energy equation was used to determine the design parameters related to the hybrid heating, ventilation, and air condition (HVAC) system. For the underground heat exchanger, it was assumed that the heat capacity ratio, R, was small in magnitude. The energy ratio estimated in the corridor of the lecture hall increased by 17% as compared to the hall area. The exergy destruction of the system was estimated to be 25%, whereas the maximum exergy gain computed at the secondary side of the geothermal unit, followed by the second fan coil, the first fan coil, and the radiator. The calculated heating rate was found to be 25.273% lower than the required sensible heat gain. The installed unit could attain the maximum energy ratio of 4.031 if the convective losses across the building material are minimised.

Energy, Economic and Environmental Analysis of Alternative, High-Efficiency Sources of Heat and Energy for Multi-Family Residential Buildings in Order to Increase Energy Efficiency in Poland

The article presents energy, economic and environmental analyses of the possibilities of using alternative, high-efficiency sources of heat and energy for the multi-family residential building located in Wrocław, Poland, in the temperate climate zone characteristic of Central Europe. For conventional, alternative and hybrid heating systems based on renewable energy sources, comparative analyses of final energy demand, demand for non-renewable primary energy, CO2 emissions, investment costs and life cycle costs were carried out. The detailed comparative analyses of the research results led to the formulation of conclusions and recommendations which may serve as guidelines for designers of multi-family residential buildings and investors. The solutions of heating and hot water preparation systems recommended in the article will enable the design and construction of buildings with no negative impact on the environment. Taking into account the economic and environmental analyses, the optimal sources of heat and energy are alternative heating systems based on highly efficient heat pumps supplied from a photovoltaic installation. Such solutions, however, have both technical and legal limitations related to the possibility of their implementation and are generally associated with higher investment costs.

Simulation and Majorization of Multi-source Relatively Complemented Heating System Based on TRNSYS

In order to make up for the shortcomings of solar energy, ground source heat pump as well as air source heat pump during heating, a new multi-complementary heating system with three heat sources is proposed. Take the Tumeteyouqi item as the object of study for program devise and load simulation on the basis of the set scheme, and TRNSYS hybrid heating system is established. The main parameters of the air source heat pump and the solar collector are optimized, and the hooke-Jeewes and Coordinate descent optimization algorithms are used to optimize the annual value of system costs, and the two algorithms are compared. Results are included the Collector area of 80m2, the Collector of 42.1875 ° inclination, Azimuth Angle of 10°. The unit area is homologous and the volume of the water box is 0.10125. The capacity of the water tank is 8.1 m3, and the heat quantity of the air source heat pump is 286200kj/h. The system reaches the optimum, and the annual value of the heating cost is reduced by 3.8%. Then the supply heating cost is reduced by 4.96%. The Hooke-Jeewes algorithm is superior to the Coordinate descent algorithm.