BENEFIT with Northeastern University: HVAC Hardware-in-the-Loop Experimental Testing of Heat Pump and Air Conditioner

This dataset includes HVAC Hardware-in-the-Loop (HIL) experimental results for a single stage, SEER 16, HSPF 9.5, 3-ton single-speed air source heat pump with 15 kW of backup auxiliary heating tested in both cooling and heating mode, and a two-stage, SEER 21, 2-ton central air conditioner tested in cooling mode for a set of outdoor temperatures and indoor setpoint temperatures. In addition to these tests, experimental tests focused on the operation of auxiliary heating for the heat pump for winter conditions were also conducted.

The laboratory experiments for transient testing of the heat pump and air conditioner were conducted using the two HIL systems in the Systems Performance Laboratory (SPL) at NREL’s Energy Systems Integration Facility (ESIF). Further information on laboratory design and capabilities of the SPL along with the architecture of HVAC HIL system can be found in: Sparn, B. F. 2018. Laboratory Resources and Techniques to Evaluate Smart Home Technology (No. NREL/CP-5500-71696). National Renewable Energy Laboratory (NREL), Golden, CO (United States). https://www.nrel.gov/docs/fy18osti/71696.pdf and the experimental setup and validation of HVAC HIL platform can be found in: Ramaraj, S. and Sparn, B. 2022. Validation of HVAC Hardware-In-the-Loop Simulation for Advanced Control Strategies in Smart Homes (No. NREL/CP-5500-82562). National Renewable Energy Lab (NREL), Golden, CO (United States). https://www.nrel.gov/docs/fy22osti/82562.pdf.

These experimental results can be used to validate how we currently model the cycling behavior of heat pumps and air conditioners. Additionally, many demand response programs implement heat pump and air conditioner control by changing the thermostat set point – these data may also be used to verify our models for heat pump and air conditioner demand response control are implemented correctly.

The Test_Matrix file describes all the indoor and outdoor test conditions for heat pump and air conditioner and the file names of data sets include information about the test conditions. A wide range of outdoor air temperatures were chosen to accommodate summer and winter conditions. In addition to operating the HVAC equipment with different outdoor temperatures, we also operate the system with different indoor temperature set points to represent different grid signals or different operating conditions. For cooling conditions, the baseline set point is 72°F. To represent Load Up signals, the setpoint is changed to 68°F. The Load Shed set point is 76°F. For heating conditions, the baseline set point was assumed to be 68°F. The Load add set point is 72°F and the Load shed set point is 64°F. The starting indoor temperature for cooling conditions was set ~2°F above the indoor setpoint temperature so that the equipment turned on quickly. Similarly, the initial indoor temperature was set ~2°F lower than setpoint for heating mode tests to ensure that heating began quickly. The return air temperature was assumed to be equal to the indoor setpoint temperature in all cases.

The experimental data are sampled at 1-second intervals. The data from thermostat at 5-minute interval are resampled and added to the corresponding file. The content of each data set is as follows:
• T_Return (C): Measured return air temperature [C]
• T_Return_SP (C): Return air temperature setpoint from E+ model, sent to HIL [C]
• T_Supply (C): Measured supply air temperature at evaporator outlet [C]
• T_Outdoor (C): Measured outdoor air temperature [C]
• T_Outdoor_SP (C): Outdoor air temperature setpoint from weather file, sent to HIL [C]
• T_Indoor (C): Measured indoor air temperature [C]
• T_Indoor_SP (C): Indoor air temperature setpoint from E+ model, sent to HIL [C]
• Outdoor Unit Power (W): Measured power of the outdoor unit [W]
• Indoor Unit Power (W): Measured power of the indoor unit [W]
• Evaporator Airflow Rate (CFM): Measured evaporator or indoor unit airflow rate sent to E+ model [CFM]
• Cooling/Heating Capacity (kW): Calculated cooling/heating capacity sent to E+ model [kW]
• T_SP_Thermostat (C): Thermostat cooling/heating setpoint temperature [C]
• T_Indoor_Thermostat (C): Thermostat indoor air temperature [C]