Efficiency Of Heat Pump Research Articles

Prediction of Evaporation Temperature in Air-Water Heat Source Heat Pump Based on Artificial Neural Network

To improve the low-temperature heating stability and performance of the air-source heat pump (ASHP), a heat transfer model was established for an air-water heat source heat pump(A-WSHP) in this study. Key factors affecting A-WSHP evaporating temperature were analyzed through simulation. An artificial neural network (ANN) prediction model for refrigerant evaporating temperature was developed using fin pitch, air velocity, air temperature, spray flow rate, spray water temperature, and droplet diameter as inputs. In the winter climate of Xiangtan City, this model predicts the refrigerant evaporating temperature and regulates it by adjusting various input parameters. Results indicate that fin pitch and droplet size significantly impact the refrigerant evaporating temperature, more so than fin thickness. The air temperature (34.78%) and spray water temperature (38.02%) have the highest weights, while fin thickness has the least influence, with a weight of 0.75%. The R2 value of the ANN refrigerant evaporating temperature prediction model is 0.974, indicating a good fit. By properly adjusting the heat pump fan and spray valve, changes in air velocity and spray flow rate can enhance the refrigerant evaporating temperature, leading to stable and efficient heat pump operation. This research not only provides a theoretical basis for the operational strategy of air-water heat pumps but also offers guidance for frost-free operation in low-temperature environments.

Comparison and regional suitability evaluation of different backfill source heat pumps using TRNSYS

As global energy demand and carbon emissions continues to rise year by year, the use of renewable energy for heating becomes increasingly urgent. This study employs solar and geothermal energy to supply heat to mining facilities. Initially, three distinct heating systems for mining areas were modeled in TRNSYS: the Backfill Source Heat Pump (BSHP), the Solar Assisted Backfill Source Heat Pump (SABSHP), and the Solar Assisted Backfill Source Heat Pump with Seasonal Heat Storage (SABSHP-SHS). Following a decade of simulation, the optimal system was identified through a comparative analysis that encompassed backfill temperature equilibrium, the inlet and outlet water temperatures for buried pipes, Coefficient of Performance (COP), Partial Load Ratio (PLR), and economic factors. Over the 10-year simulation period, the COP and PLR of the SABSHP-SHS system outperformed both the BSHP and SABSHP systems, showing higher energy efficiency and better heat pump performance. To further assess the regional adaptability of the SABSHP-SHS system, simulations were conducted across four regions with diverse climatic profiles: Shijiazhuang, Yan’an, Xining, and Hegang. The analysis focused on heat collection, efficiency, backfill temperature variation, system energy consumption, and the energy efficiency ratio. The findings indicate that Hegang exhibits the highest solar heat collection efficiency at 89.9% during the non-heating season, while Xining achieves a significantly higher heat collection efficiency of 54.1% during the heating season. These results suggest that the SABSHP-SHS system is particularly effective in regions with pronounced seasonal variations, characterized by extended cold winters and brief, intense summers.

Energy, exergy, economic and environmental studies on a nonflammable eco-friendly mixture for efficient heating in cold regions

As a compelling alternative to fossil fuel combustion, air-source heat pumps face challenges in inefficiency, flammability, and pollution when operated at low ambient temperatures. To address the demand for safe, eco-friendly and efficient heating during wintertime, this work is devoted to exploring a novel refrigerant for air-source heat pumps. The zeotropic mixture has the potential to meet all the above demands at appropriate operating parameters, although specific feasible mixtures are still under investigation. In this work, a novel mixture of carbon dioxide and trans-1,1,1,4,4,4-hexafluoro-2-butene is proposed, with the heating performance being parametrically optimized based on a genetic algorithm. Energy analysis indicates a coefficient of performance improvement of up to 15.7 %, and thus an improvement in heating seasonal performance factor of more than 13.5 % for different cities, compared with traditional configurations. Exergy analysis shows that the low irreversibility of throttling is the main contributing factor to the improvement in energy efficiency. Meanwhile, economic and environmental analyses reveal a payback period of less than 7.5 years and an annual cost reduction of up to 14.5 %, as well as a carbon dioxide emission reduction of over 15.7 %. The sensitivity of operating parameters is analyzed, and other advantages of this concept are discussed as well. The results indicate a safe, efficient, environmentally friendly, and cost-effective air-source heat pump. This study contributes to: 1) providing an energy-efficient and environmentally friendly alternative refrigerant for heat pumps; and 2) promoting the sustainable development of low-carbon energy transformation technology.

Experimental study on the characteristics of frost formation and defrosting water retention between vertical double surfaces with different wettability

Frost formation and defrosting water retention directly affect the heat transfer process of outdoor finned tube heat exchanger, which in turn influences the energy efficiency of air source heat pumps for building heating. Three typical wettability surfaces were prepared, including a bare copper hydrophilic surface (BCS), a hydrophobic copper surface (HCS) and a superhydrophobic copper surface (SHCS). The above three surfaces are combined in pairs to construct three different wettability combinations, which are Combination 1: HCS-BCS, Combination 2: BCS-SHCS and Combination 3: HCS-SHCS, respectively. Frosting-defrosting experiments between vertical double surfaces are carried out on the above combinations. The results illustrated that the combinations with SHCS exhibit excellent frost inhibition properties. Compared with Combination 1, the channel filling rate of Combination 2 and Combination 3 were reduced by 16.79 % and 30.09 % respectively at a frosting time of 60 min. The defrosting time of the combination is determined by the slower defrosting of the two surfaces. Compared with Combination 2, the defrosting rate of Combination 3 is improved by up to about 12.93 %. Avoiding the formation of large-sized liquid films and droplets or utilizing the “absorption” phenomenon caused by wettability differences between surfaces are important measures to reduce the possibility of bridge formation during the defrosting process. And the greater the wettability difference, the more obvious the “absorption” phenomenon became. Spherical droplets on the SHCS can be completely absorbed by the liquid film on BCS under the action of differential surface tension. Neither Combination 2 nor Combination 3 formed a liquid bridge at a surface spacing of 2 mm. The research will provide theoretical support for the selection of fin spacing and fin coating type under different working conditions in practical engineering.

Distributed multienergy and low-carbon heating technology for rural areas in northern China

In the context of China's “double carbon” policy and “rural revitalization” strategy, clean and low-carbon heating in rural areas of the northern China has become a key problem that needs to be urgently addressed. Practice has proved that “coal-to-gas” and “coal-to-electricity” projects have various limitations, such as high operating cost, high carbon emission, and high cost of distribution network upgrade, making them unsuitable for nationwide promotion. To address this issue, this research proposes a distributed multienergy and low-carbon heating (DMLH) system, which integrates the photovoltaic power generation, combined heat and power (CHP) system, heat storage, and newly developed multisource efficient heat pump (MEHP). The MEHP operates by simultaneously absorbing heat from air and waste heat sources of the CHP generation, providing a stable and efficient heat output. The multienergy complementary operating strategy of the DMLH system has been presented, considering variations of heating demand and environmental temperature. Comprehensive case studies were performed under typical and extremely cold winter scenarios to examine the effectiveness of the DMLH system. Simulation results revealed that 66.7 % of the operating cost can be reduced by the proposed system in typical scenario and the heat supply stability of MEHP has been considerably enhanced compared to a single-stage heat pump system. Furthermore, the DMLH system has low-level requirement of distribution network capability, which is conducive to promotion in the rural areas of northern China.

HAPPENING: an efficient cascade heat pump system for multifamily buildings

An innovative hybrid heat pump system is presented as a novel solution for multifamily building heating system retrofitting. This system is very efficient on the one hand thanks to its innovative configuration in cascade, minimum thermal losses and on the other hand, the maximization of local solar energy self-consumption due to decoupling generation and consumption and applying smart control strategies. It is aimed at facilitating retrofitting of existing heating systems in multifamily buildings, enabling an efficient decarbonization. Three variations of the system have been designed, installed, and tested in real buildings across Europe, within the H2020 project “HAPPENING”. The project is now under monitoring phase and the preliminary results are positive, demonstrating the high efficiency of the concept

Performance analysis of PEMFC-assisted renewable energy source heat pumps as a novel active system for plus energy buildings

The adoption of plus energy buildings (PEBs) has been considered extensively in various nations for carbon neutralization. However, studies on suitable active systems that can efficiently supply heating, cooling, and electrical energy to PEBs are lacking. This study proposes PEMFC-assisted renewable energy source heat pumps (PEMFC-RSHPs) as active systems for plus energy buildings. In the steady-state simulations using TRNSYS, the waste-heat recovery effect was investigated at various current densities and PEMFC temperatures. In the transient simulations, the seasonal operating characteristics, energy, economic, and environmental performances of PEMFC-RSHPs using air, raw-water, and ground energy sources were analyzed. During the heating season, the maximum primary energy efficiency (PEF) of a PEMFC-assisted ground source heat pump (GSHP) was approximately 0.252 at an optimal current density of 0.8 A cm−2. However, during the cooling season, the PEMFC-assisted raw-water source heat pump (RWSHP) showed the highest PEF of 0.407 at an optimal current density of 0.7 A cm−2. In addition, the CO2 emissions of the PEMFC-GSHP using green hydrogen were 54.3% lower than those using gray hydrogen, although the economic feasibility was still challenging. In conclusion, the PEMFC-GSHP using green hydrogen is the most feasible active system for PEBs.

Enhancing geothermal heat pump efficiency with fin creation and microencapsulated PCM: A numerical study

The main cause of global warming is the emission of carbon dioxide from fossil fuels. Several methods to reduce CO2 emissions have been explored to ensure energy conservation. Many researchers have focused on renewable energy sources for this reason. Ground-source heat pumps (GSHPs) have emerged as a popular alternative in various sectors that utilize shallow geothermal energy sources for heating and cooling. This study presents a novel approach to enhancing the efficiency of geothermal heat exchangers, a critical component of GSHPs, through numerical simulation using computational fluid dynamics (CFD) with Ansys Fluent software. The research investigates the impact of adding four models of spiral fins to the exterior body of the heat exchanger: single spiral and double spiral configurations with pitches of 60 mm and 40 mm, respectively. Additionally, the study explores the effect of incorporating microencapsulated phase change materials (PCMs) with volume fractions of 0 %, 10 %, 30 %, and 50 % into the backfill material surrounding the heat exchanger. The results demonstrate that the double spiral fins with a 40 mm pitch significantly enhance thermal efficiency by reducing the output temperature by up to 1 °C compared to the model without fins. Furthermore, the addition of 50 % microencapsulated PCM by volume to the backfill material can further decrease the output temperature by up to 4 °K. The combined use of double spiral fins and microencapsulated PCMs results in a 7.5 % improvement in the efficiency of the heat exchanger and the coefficient of performance of the heat pump. This study highlights the potential of innovative design modifications and material enhancements to significantly improve GSHP performance for more efficient and sustainable heating and cooling solutions.

Dust removal by water spray, condensation and defrosting based on superhydrophobic fin surface

Dust deposition on the fin surface of the outdoor heat exchanger seriously affects the operating efficiency of the air source heat pump (ASHP). Considering the operation characteristics of ASHP in summer for cooling and in winter for heating, a dust removal strategy is proposed based on superhydrophobic fin surface (SFS). In summer, the SFS is sprayed to remove dust by collecting the condensate water of air conditioning. In winter, by coupling the dust deposition with the condensation or frosting/defrosting phenomenon on SFS, the self-propelled motions of condensate droplets or the peeling off of the frost layer in defrosting is used to realize the dust removal. The experiment results show that the water spray on SFS has excellent dust removal performance, and the deposited dust is completely removed after 2 sprays. The dust is carried away by the jumping or gliding of the water droplets. The condensation has poor dust removal performance and takes long removal time. After several hours of condensation, the dust removal rate is 89.6 % and 40.0 % on SFS under different dust deposition levels. Due to the peeling off of the frost layer from the SFS at beginning of defrosting, the melting water at the bottom of the frost layer carries the dust away from the fin surface effortlessly. After 2 defrosting cycles, the dust removal rate reaches 99.6 %, while it is 50.1 % on the bare surface. Therefore, the strategy of dust removal by water spray in summer and defrosting in winter is suitable for ASHP.

Achieving equitable space heating electrification: A case study of Los Angeles

A major step towards residential building decarbonization is the electrification of natural gas space heating. Current inequities such as limited access to cooling technologies and high energy burden can be addressed in transition if we take steps now to understand the economic impacts of different electric technologies. This study presents a novel high-resolution techno-economic model, the Marginal Net Present Value Upgrade Analysis model, which improves upon existing literature that examines the economics of electrifying space heating through a more detailed cost calculation and the use of a variable discount rate. Results show that 1) electrifying with heat pumps is only recommended for owners who are replacing a natural gas furnace and central AC system, 2) renters are highly vulnerable in this transition in that electric resistance technologies are the least capital intensive technology for landlords to install, with renters bearing the increased operational cost, 3) rebates from the Inflation Reduction Act of 2022 allow most qualifying landlords and owners to install even the highest efficiency heat pumps at a net savings when compared to the baseline heating and cooling system, and 4) reducing capital costs are more critical than altering utility rates to achieve high heat pump penetration. The model developed herein can support decision-making related to electrification and energy efficiency policy and rulemaking and will give insight into the impact residential building electrification can have on marginalized communities.

Impact of temperature dependent coefficient of performance of heat pumps on heating systems in national and regional energy systems modelling

To successfully transition towards fully renewable energy systems, energy sectors that today are primarily autonomous should be closely integrated to increase system flexibility and maximise synergy from effective sector coupling. Heat pumps are one of the sector coupling technologies which enable a mutual integration of power and heat sectors. Heat pumps are viewed as a low-cost source of sustainable heat for both space heating and industrial processes. However, representation of heat pumps in energy system models is typically oversimplified by using a uniform coefficient of performance, which limits perception of the hourly temperature changes on heat pump efficiency, or by using generic heat pumps for all individual residential, district, or industrial heat supplies. The LUT Energy System Transition Model was expanded to examine the impact of utilisation of hourly coefficient of performance profiles and specific heat pumps for different applications. The results indicate that, in cold climate countries, the use of hourly coefficient of performance profiles has little impact on the heat supply structure and overall primary energy demand, but has a noticeable impact on the electricity supply and energy storage system. Though the cost of the optimised system stays on the same level, application of hourly COP profiles leads to a more accurate simulation of electricity consumption and energy storage operation. The separation of district and industrial heat pumps leads to a higher share of heat pumps in industrial heat supply and allows for a reduction in overall energy system primary energy demand by 1.8%.

Dual Impacts of Space Heating Electrification and Climate Change Increase Uncertainties in Peak Load Behavior and Grid Capacity Requirements in Texas

AbstractAround 60% of households in Texas currently rely on electricity for space heating. As decarbonization efforts increase, non‐electrified households could adopt electric heat pumps, significantly increasing peak (highest) electricity demand in winter. Simultaneously, anthropogenic climate change is expected to increase temperatures, the potential for summer heat waves, and associated electricity demand for cooling. Uncertainty regarding the timing and magnitude of these concurrent changes raises questions about how they will jointly affect the seasonality of peak demand, firm capacity requirements, and grid reliability. This study investigates the net effects of residential space heating electrification and climate change on long‐term demand patterns and load shedding potential, using climate change projections, a predictive load model, and a direct current optimal power flow (DCOPF) model of the Texas grid. Results show that full electrification of residential space heating by replacing existing fossil fuel use with higher efficiency heat pumps could significantly improve reliability under hotter futures. Less efficient heat pumps may result in more severe winter peaking events and increased reliability risks. As heating electrification intensifies, system planners will need to balance the potential for greater resource adequacy risk caused by shifts in seasonal peaking behavior alongside the benefits (improved efficiency and reductions in emissions).

High-temperature heat pumps: Fundamentals, modelling approaches and applications

In March 2023, the European Parliament and Council reached a consensus to increase the binding renewable energy target (RES) to a minimum of 42.5 % by 2030, effectively doubling the proportion of RES from the 2020 baseline. This significant development aligns the EU more closely with the objectives of the European Green Deal and the REPowerEU initiative. High-temperature heat pumps (HTHP), due to their appropriateness for industrial-scale applications, integrate perfectly within this progressive trajectory. They enable waste heat generated by various production processes to be recovered (temperatures typically ranges from around 50 °C–100 °C) and subsequent use at temperatures above 100 °C, thus reducing the consumption of fossil fuels and greenhouse gas emissions. The high operating temperatures and pressures of HTHPs are challenging. They require an in-depth analysis of the system processes involved, taking into account refrigerants, efficient heat pump cycles and key components. One possibility for a preliminary analysis of vapour compression HTHP system performance without incurring the costs associated with manufacturing and testing the device is modelling. However, there is no comprehensive review of research work on possible software. Commonly, the researchers report on one chosen methodology and the tools used. This paper provides a comprehensive review of modelling approaches. It also discusses aspects related to the principles of operation, refrigerants and system components. Additionally, the paper presents an overview of vapour compression heat pump applications in various sectors. The literature review conducted indicates the need for further research and development of HTHP covering not only technological aspects but also software development.

Techno-Economic Evaluation of CSP–PV Hybrid Plants with Heat Pump in a Temperature Booster Configuration

Concentrated solar power (CSP)—photovoltaic (PV) hybrid power plants allow for the generation of cheap electrical energy with a high capacity factor (CF). A deep integration of both technologies offers synergies, using parts of the PV generated electricity for heating the thermal storage tank of the CSP unit. Such configurations have been previously studied for systems coupled by an electric resistance heater (ERH). In this work, the coupling of a CSP and a PV plant using a heat pump (HP) was analyzed due to the higher efficiency of heat pumps. The heat pump is used as a booster to lift the salt temperature in the storage system from 383 to 565 °C in order to reach higher turbine efficiency. A techno-economic analysis of the system was performed using the levelized cost of electricity (LCOE), the capacity factor and nighttime electricity fraction as variables for the representation. The CSP–PV hybrid with a booster heat pump was compared with other technologies such as a CSP–PV hybrid plant coupled by an electric heater, a standalone parabolic trough plant (PT), a photovoltaic system with battery storage (PV–BESS), and a PV thermal power plant (PVTP) consisting of a PV plant with an electric heater, thermal energy storage (TES) and a power block (PB).

Experimental Studies and Performance Characteristics Analysis of a Variable-Volume Heat Pump in a Ventilation System

Air-to-air heat pumps are used in today’s ventilation systems increasingly often as they provide heating and cooling for buildings. The energy transformation modes of these units are subject to constant change due to the varying outdoor air state, including temperature and humidity. When choosing how to operate and control energy transformers, it is important to be able to adapt effectively to the changing outside air conditions. Nowadays, modern commercial heat pumps offer two levels of control flexibility: a compressor with a variable speed and an electronic expansion valve. This combination of control elements has boosted the seasonal energy efficiency of heat pumps. For a long time, cycle control possibilities have been dominated by electronic controls. The authors of this paper aim to present an additional element to the traditional heat pump controls, which provides a third level of control over the cycle. To achieve the objective, experimental investigations of a heat pump integrated into a ventilation unit have been carried out under real-life conditions. The experiments involved varying the operating modes of the unit by adjusting the compressor speed, the position of the expansion valve, and the volume of the system loop. The study examined the performance characteristics of the heat pump and found that the performance of a variable-volume heat pump is comparable to that of a conventionally operated typical constant-volume heat pump system. In addition, the study found that by adding a third level of volume control to the active heating circuit, in combination with conventional controls, the heat pump’s heat output range could be extended by 69.62%. The study determined the variation of the heat pump cycle in the p-h diagram with the variation of the loop volume. The benefits and drawbacks of a heat pump with a variable-volume loop are discussed in this study.

Local entropy generation optimization and thermodynamic irreversibility analysis of oval-shaped coaxial ground heat exchangers: A detailed numerical investigation

Optimizing the heat transfer and thermodynamic efficiency of Ground Heat Exchangers (GHE) is crucial for maximizing the energy efficiency of Ground-coupled Heat Pump (GCHP) systems utilized in building heating and cooling applications. This study pioneers an effective approach of both the first and second laws of thermodynamics of the newly oval-shaped coaxial GHEs (oval-CGHEs), assessing heat transfer, thermohydraulic performance, and local entropy generation rate to explore the optimum design and operational conditions for heat exchange maximization and entropy generation minimization. Utilizing a three-dimensional numerical model validated by experimental results, this study examines the trade-offs between heat transfer improvements and entropy generation rate intensification of the oval-CGHEs in comparison to the typical circular-shaped CGHE (circle-CGHE) further than exploring the effect of key operational and design parameters and performing sensitivity analysis. The results reveal that oval-CGHEs exhibit higher irreversibility as a penalty for their superior heat transfer capabilities compared to traditional circular-shaped CGHEs (circle-CGHE), which can be mitigated by optimizing the position of the inner tube. Moreover, the study underscores the criticality of maintaining a balance between enhanced heat transfer and the associated rise in irreversibility, particularly concerning the factors of mass flow rates and installation depths.

Cooling and heating innovations: exploring the diverse applications of heat pumps

Heat pumps are versatile and energy efficient devices that play a crucial role in modern heating, cooling, and refrigeration applications. This paper provides a concise overview of the diverse applications and benefits of heat pumps across residential, commercial, industrial, and transportation sectors. The paper discusses the principles of heat pump operation, emphasizing their capability to transfer heat from one location to another using thermodynamic processes. The work highlights key applications such as residential heating, ventilation, and air conditioning systems, commercial refrigeration, hot water heating, process cooling, and renewable energy integration. The energy efficiency and environmental benefits of heat pumps are also emphasized, showcasing their potential to reduce carbon emissions and contribute to sustainable energy practices. By understanding the broad scope of heat pump applications outlined in this work, researchers, engineers, policymakers, and industry stakeholders can gain insights into the significance of heat pump technology in advancing energy efficiency and addressing climate change challenges.

Lifecycle carbon footprints of buildings and sustainability pathways in China

The Paris Agreement, with a 2 °C temperature increase baseline and a 1.5 °C target temperature increase, imposes challenges to the sustainability of buildings. However, as an end-user or end-of-the-art, the building sector overlaps with other sectors, such as industry and transportation in building materials manufacturing (such as steel, concrete, cement, etc. ) and electricity use (such as building-to-vehicle charging), imposing difficulties in lifecycle carbon footprint quantification in buildings. In this study, the lifecycle carbon footprint of buildings and sustainability pathways in China are provided. Tools and platforms for lifecycle carbon footprint quantification in buildings are reviewed. A global database for lifecycle carbon footprint quantification in buildings is reviewed and compared, together with an analysis of the advantages and disadvantages. Furthermore, decarbonization technologies in the building operation stage are comprehensively reviewed, including the decarbonization potential, technology readiness level (TRL), techno-economic performance, and current technical status. Pathways on carbon neutrality in building sectors in China are provided. The results indicate that inconsistencies in global databases, unclear definitions of lifecycle carbon emissions, and inaccurate models of building energy consumption are the main challenges for accurate lifecycle carbon analysis in buildings. Various carbon neutrality transformation technologies can be classified into ultralow energy building and near zero-energy building technologies and into efficient heat pump and smart metering technologies. Pathways for low-carbon transition in building sectors include building energy saving (330 million tCO2 with 22%), renewable energy supply (299 million tCO2 with 20%), building electrification and power sector decarbonization (450 million tCO2 with 30%), and carbon capture, utilization and storage (CCUS) technology (420 million tCO2 with 28%). These research results can pave the way for upcoming studies on the lifecycle carbon footprint in buildings and sustainability pathways in China.

Energy Savings, Environmental Impacts and Monitoring Results of a Pumped Solar Water Heating System at Katutura Hospital Maternity Ward, Namibia

The SADC region is endowed with solar radiation between 1800-2400 kWh/m2 [1]. Nevertheless only 0.3 % of the worldwide solar thermal capacity is installed in the Sab-Saharan African Countries. Therefore, the main goal of the Southern African Solar Renewable Heating and Cooling Initiative (SOLTRAIN+) project funded by the Austrian Development Agency is to contribute to the transformation of the energy system to a sustainable, affordable and carbon-free system. This will be done by the implementation of Renewable, Heating and Cooling (RHC) systems in the targeted sectors: buildings, industry & commerce, tourism and hospitals, and enable this by a holistic capacity building. RHC technologies are solar thermal, heat pump and energy efficiency. This study therefore intends to evaluate and produce energy balance, based on real data recorded from January 2023 to December 2023 on a 120 m2 collector area with 8000 litres storage tanks, and a 22 kW heat pump, installed at Katutura State Hospital maternity ward.

Real-time monitoring and optimization of a large-scale heat pump prone to fouling - towards a digital twin framework

Large-scale heat pumps are a promising technology for the decarbonisation of heat supplied in buildings and industries, provided they operate as expected. However, common faults like fouling and unplanned downtime periods can significantly affect their performance and availability. This could limit the widespread adoption of large-scale heat pumps over other heating technologies such as gas and electric boilers. Approaches described in the literature to optimize the operation of large-scale heat pumps often lack validation under real-world conditions and do not account for performance degradation due to faults. This work demonstrates a step towards utilizing digital twins to improve the energy performance of a commercial large-scale heat pump affected by fouling. A framework was proposed based on the real-time adaptation of digital twins, where a simulation model was calibrated online based on measurements from the heat pump in operation, which was then used for set point optimization. This enabled to determine optimal intermediate pressure set points in the heat pump operating under varying levels of fouling over time. The framework was tested on different periods of heat pump operation spread over ten calendar months. The results showed that the use of online calibration rather than a single calibration decreased performance estimation errors between 3 and 17 percentage points. Moreover, the set points determined by the online-calibrated model, along with a simpler polynomial model derived from it, showed improvements in the heat pump performance by up to 3%, depending on the level of fouling. The findings of this study demonstrated the potential to extend the proposed framework using digital twins to enhance the energy efficiency of large-scale heat pumps.