Heating seasonal performance factor (HSPF) of 3.65

Researchers from Beijing University of Civil Engineering and Architecture in China have developed a new control strategy for PV-driven air source heat pumps (ASHPs) to optimize energy efficiency and system performance. The study focused on variable water temperature and variable flow rate configurations, comparing three innovative designs—CV-ASHP (constant water temperature, variable flow), VC-ASHP (variable water temperature, constant flow), and VV-ASHP (variable water temperature, variable flow)—against a conventional CC-ASHP (constant water temperature, constant flow) system. The VV-ASHP system , powered by solar photovoltaic (PV) energy, demonstrated the highest energy-saving efficiency (24.13%) and superior seasonal performance metrics, including a seasonal energy efficiency ratio (SEER) of 2.60, a heating seasonal performance factor (HSPF) of 3.65, and an annual performance factor (APF) of 2.99. The proposed control strategy increases the energy efficiency of optimized building systems by 18% and reduces their carbon content by 37.78% through solar energy integration.

Data Extracted:

System Configurations:

1. Conventional System (CC-ASHP):

   • Constant water temperature, constant flow.

2. Optimized Systems:

   • CV-ASHP: Constant water temperature, variable flow.

   • VC-ASHP: Variable water temperature, constant flow.

   • VV-ASHP: Variable water temperature, variable flow, with a temperature regulator (temperature sensor, water temperature sensor, and controller).

3. Energy Source:

   • The VV-ASHP system operates with PV energy support, exporting excess power to the grid during high solar radiation and using grid electricity during low solar radiation.

Performance Metrics:

1. Annual Energy-Saving Efficiency:

   • CV-ASHP: 12.00%

   • VC-ASHP: 13.11%

   • VV-ASHP: 24.13%

2. Seasonal Performance Improvements (VV-ASHP):

   • Cooling season: 25.2% increase in energy-saving efficiency

   • Heating season: 20.6% increase in energy-saving efficiency

3. Key Performance Ratios (VV-ASHP):

   • SEER (Seasonal Energy Efficiency Ratio): 2.60

   • HSPF (Heating Seasonal Performance Factor): 3.65

   • APF (Annual Performance Factor): 2.99

4. Annual Energy-Saving Rate Comparisons (VV-ASHP vs. Others):

   • VV-ASHP vs. CC-ASHP: 37.8% higher

   • VV-ASHP vs. CV-ASHP: 18.0% higher

   • VV-ASHP vs. VC-ASHP: 28.4% higher

   • VV-ASHP vs. itself without solar coupling: 29.3% higher

Carbon Reduction Potential:

1. Solar Energy Contribution:

   • Solar PV integration reduces the carbon content of building systems by 37.78% .

System Design and Operation:

1. Components:

   • ASHP unit, heat storage tank, end air conditioning box, water pump.

2. Water Flow Process:

   • Water circulates between the heat storage tank and ASHP for heating/cooling, then returns to the tank. Treated water is sent to the end air conditioner for room conditioning and recirculated as needed.

3. Control Strategy Focus:

   • Designed for scenarios with weak dynamic control of building air conditioning systems and underutilized PV energy. Ensures cooling/heating capacity meets room load requirements.

Applications:

1. Building Energy Optimization:

   • Suitable for buildings requiring efficient heating and cooling systems with renewable energy integration.

2. Carbon Reduction Goals:

   • Aligns with global efforts to decarbonize building energy systems through renewable energy and advanced control strategies.

Research Context:

1. Publication Details:

   • Paper Title: “ASHP system based on a solar photovoltaic coupling study of a control strategy for variable water temperature and variable flow”

   • Published in: Journal of Building Engineering

2. Corresponding Author:

   • Xiaojun Wu , Beijing University of Civil Engineering and Architecture

3. Key Findings:

   • The VV-ASHP system outperforms other configurations in energy efficiency, making it ideal for sustainable building systems.

   • Solar PV integration significantly enhances energy savings and reduces carbon emissions.