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Outline
To address the heating capacity attenuation of air‑source heat pumps under low‑temperature conditions，an experimental setup with a flash tank for vapor injection was established to investigate the influence of parameters such as intermediate refrigerant pressure and superheat degree on system performance under superheated vapor injection conditions.The results show that the flow rate and state of the injected refrigerant are key factors.When the vapor injection pressure increases，the superheat degree decreases and the refrigerant dryness approaches 1.As the electronic expansion valve opening increases from 10% to 40%，the vapor injection pressure rises from 1.48 MPa to 1.79 MPa under minimum operating conditions and from 1.01 MPa to 1.71 MPa under low‑temperature operating conditions.Both the vapor injection enthalpy increment and heating coefficient of performance （COP） exhibit a trend of first increasing and then decreasing，with an overall improvement in heating capacity.When the electronic expansion valve opening is approximately 25%，the COP reaches 3.64 under minimum operating conditions and a maximum value of 2.62 under low‑temperature operating conditions.Maintaining the injected refrigerant close to saturated vapor state is an important control factor，while the theoretically optimal enthalpy‑increasing pressure is not universally applicable.This study can provide references for the design，operation，and control of low‑temperature heat pump water heaters.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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