US 12,292,220 B2
Multi-parallel carbon dioxide heat pump control method based on target load control
Dan Xiong, Jiangsu (CN); Xiaoliang Tang, Jiangsu (CN); Hao Pan, Jiangsu (CN); Qiang Kang, Jiangsu (CN); Xiaofei Song, Jiangsu (CN); and Jun You, Jiangsu (CN)
Assigned to Jiangsu Sujing Group Co., Ltd., Jiangsu (CN)
Filed by JIANGSU SUJING GROUP CO., LTD., Jiangsu (CN)
Filed on May 19, 2022, as Appl. No. 17/664,203.
Application 17/664,203 is a continuation of application No. PCT/CN2019/122571, filed on Dec. 3, 2019.
Claims priority of application No. 201911186969.1 (CN), filed on Nov. 28, 2019.
Prior Publication US 2022/0282892 A1, Sep. 8, 2022
Int. Cl. F25B 9/00 (2006.01); F25B 30/02 (2006.01); F25B 49/02 (2006.01)
CPC F25B 9/008 (2013.01) [F25B 30/02 (2013.01); F25B 49/022 (2013.01); F25B 2309/061 (2013.01); F25B 2600/02 (2013.01); F25B 2600/2513 (2013.01)] 10 Claims
OG exemplary drawing
 
1. A multi-parallel carbon dioxide heat pump control method based on target load control, wherein the multi-parallel carbon dioxide heat pump comprises a carbon dioxide circulation loop, a heat source pipeline and a hot water pipeline, wherein the carbon dioxide circulation loop comprises an evaporator evaporating pipe, a gas-liquid separator, a compressor unit, an oil-gas separator, a cooler condensing pipe and an electronic expansion valve which are arranged in series in the loop sequentially; the evaporator evaporating pipe and the heat source pipeline are arranged together to exchange heat with each other; the hot water pipeline and the cooler condensing pipe are arranged together to exchange heat with each other; the compressor unit comprises a plurality of variable-frequency carbon dioxide compressors arranged in parallel; the hot water pipeline is provided with a water pump and a flow meter, and an inlet end and an outlet end of the hot water pipeline are respectively provided with a temperature sensor, wherein the control method comprises adjusting an opening degree of the electronic expansion valve according to an inlet temperature of the hot water pipeline, an outlet temperature of the hot water pipeline, a flow in the hot water pipeline and a target outlet temperature set by a user;
wherein the control method comprises following steps:
1) obtaining the inlet temperature Thi of the hot water pipeline, the outlet temperature Tho of the hot water pipeline and the flow V of the hot water pipeline, and according to the target outlet temperature Tobj set by a user, calculating a target heating capacity Q=1.163*(Tobj-Thi) *V, and calculating a current heating capacity Qc=1.163*(Tobj-Tho) *V;
2) when each carbon dioxide compressor is set to run at 50 Hz, the load of the carbon dioxide heat pump system is 100%, the number of the carbon dioxide compressors provided in the multi-parallel carbon dioxide heat pump is N, and according to the rated working conditions, the rated heating capacity of each carbon dioxide compressor is Qs, thus a target load L=Q/(N*Qs)*100%, and an actual load Lr=Qc/(N*Qs)*100%;
3) according to the target load L, the actual load Lr, the number n of variable-frequency carbon dioxide compressors, an upper limit Fmax and a lower limit Fmin of variable frequency of the variable-frequency carbon dioxide compressors, calculating a target opening degree of the electronic expansion valve

OG Complex Work Unit Math
wherein, A, B and C are respectively specific coefficients, and A, B and C obtained by different equipments are different, and N is total number of the carbon dioxide compressors included in the multi-parallel carbon dioxide heat pump;
4) adjusting the opening degree of the electronic expansion valve according to the target opening degree Ke of the electronic expansion valve.