System Optimization and Operating Strategy of Single-Stage Air Source Heat Pump with Thermal Storage to Reduce Wind Power Curtailment
Abstract
1. Introduction
2. Materials and Methods
2.1. Basic Data
2.2. Integrated Heating System Configuration
2.3. Operating Strategies
2.3.1. Strategy A
2.3.2. Strategy B
2.4. TRNSYS Modeling
2.4.1. Target Building
2.4.2. Equipment Selection
- αi = 1, if fluid from heat source enters node i, 0 otherwise
- βi = 1, if fluid returning from load enters node i, 0 otherwise
- γi = 1, if the net flow m(i−1) enters node i from the node above
- = −1, if the net flow m(i−1) goes from node i to the node above
- = 0, if there is no flow stream between node i and the node above
- δi = 1, if the net flow m(i+1) enters node i from the node below
- = −1, if m(i+1) goes from node i to the node below
- = 0, if m(i+1) = 0
- ε = 1, if auxiliary electric heater is on, 0 otherwise
3. Results and Discussion
3.1. Water Tank Size and Storage Temperature Set Point
3.2. Auxiliary Electric Heating Power
3.3. Comparison of Operating Strategies
4. Conclusions
- The size of the water tank and the storage temperature set point determined the system’s ability to shift during peak load. For specific applications, a proper combination of the two parameters existed to minimize energy consumption while satisfying the heating demand of users.
- The use of auxiliary electric heating to raise the storage temperature was necessary for conventional single-stage air source heat pumps to participate in wind curtailment reduction. Different system operating strategies require different capacities for auxiliary heating.
- By implementing a proper operating strategy, the non-renewable power consumption could be reduced by 11% for the studied building, with a total wind power utilization of 3348 kWh during the heating season while still satisfying the heating demand of users.
Author Contributions
Funding
Data Availability Statement
Conflicts of Interest
Nomenclature
m | fluid flow rate (kg/s) |
C | fluid heat transfer coefficient (kJ/kg·K) |
T | temperature (°C) |
Q | heat flow rate (kW) |
V | volume of tank (m3) |
H | height of the tank (m) |
U | heat loss coefficient (W/(m2·K)) |
L | circumference of tank (m) |
Subscript | |
i | the ith node |
fl | fluid |
heat | heat source side |
load | load side |
aux | auxiliary electric heater |
loss | loss of heat |
bot | bottom of the tank |
top | top of the tank |
N | number of tank layers |
t | tank |
env | environment |
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Parameter | Value |
---|---|
Rated heating capacity (kW) | 63 |
Rated Input Power (kW) | 16.5 |
Rated COP | 3.82 |
Rated air volume of evaporator (m3/h) | 22,000 |
Rated air volume of evaporator (m3/h) | 10.9 |
Component | Parameter | TRNSYS Type |
---|---|---|
Thermal storage pump | Rated power = 0.75 kW; Rated flow rate = 10,980 kg/h | Type114 |
water pump | Rated power = 0.55 kW; Rated flow rate = 3760 kg/h | Type114 |
PID controller | Proportional coefficient = 4 Integral coefficient = 1.7 | Type23 |
Fan coil unit | Discharge air temperature = 30 °C Rated air flow = 10,200 m3/h | Type753e |
Storage Temperature Set Point (°C) | Water Tank Size (m3) | Strategy A | Strategy B | ||
---|---|---|---|---|---|
Hours of Thermal Discomfort | Thermal Storage Energy Consumption (kWh) | Hours of Thermal Discomfort | Thermal Storage Energy Consumption (kWh) | ||
50 | 2.00 | 113 | 1108.73 | 91 | 1178.53 |
50 | 2.20 | 98 | 1238.94 | 78 | 1304.27 |
50 | 2.40 | 90 | 1366.97 | 68 | 1425.43 |
50 | 2.60 | 72 | 1523.29 | 54 | 1533.11 |
50 | 2.80 | 58 | 1630.47 | 42 | 1634.19 |
50 | 3.00 | 49 | 1724.90 | 33 | 1722.13 |
55 | 2.00 | 44 | 2330.70 | 32 | 2435.88 |
55 | 2.20 | 30 | 2546.44 | 18 | 2639.00 |
55 | 2.40 | 19 | 2789.02 | 7 | 2841.17 |
55 | 2.60 | 7 | 2986.21 | 2 | 3023.50 |
55 | 2.80 | 5 | 3167.49 | 0 | 3206.68 |
55 | 3.00 | 0 | 3352.91 | 0 | 3243.54 |
60 | 2.00 | 5 | 3453.57 | 2 | 3486.88 |
60 | 2.20 | 2 | 3735.23 | 0 | 3740.52 |
60 | 2.40 | 0 | 3995.01 | 0 | 3988.44 |
60 | 2.60 | 0 | 4233.84 | 0 | 4215.70 |
60 | 2.80 | 0 | 4424.49 | 0 | 4416.32 |
60 | 3.00 | 0 | 5013.63 | 0 | 5020.79 |
Energy Consumption by Heat Pump (kWh) | Energy Consumption by Electric Heater (kWh) | Heat Pump COP during Charging Period | |
---|---|---|---|
Strategy A | 956 | 2349 | 2.71 |
Strategy B | 968 | 2190 | 2.64 |
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Ren, Q.; Gao, C.; Jia, J. System Optimization and Operating Strategy of Single-Stage Air Source Heat Pump with Thermal Storage to Reduce Wind Power Curtailment. Buildings 2024, 14, 1993. https://doi.org/10.3390/buildings14071993
Ren Q, Gao C, Jia J. System Optimization and Operating Strategy of Single-Stage Air Source Heat Pump with Thermal Storage to Reduce Wind Power Curtailment. Buildings. 2024; 14(7):1993. https://doi.org/10.3390/buildings14071993
Chicago/Turabian StyleRen, Qianyue, Chuang Gao, and Jie Jia. 2024. "System Optimization and Operating Strategy of Single-Stage Air Source Heat Pump with Thermal Storage to Reduce Wind Power Curtailment" Buildings 14, no. 7: 1993. https://doi.org/10.3390/buildings14071993
APA StyleRen, Q., Gao, C., & Jia, J. (2024). System Optimization and Operating Strategy of Single-Stage Air Source Heat Pump with Thermal Storage to Reduce Wind Power Curtailment. Buildings, 14(7), 1993. https://doi.org/10.3390/buildings14071993