In order to evaluate the heating performance of gas engine heat pump（GEHP） for air-conditioning and hot water supply, a test facility was developed and experiments were performed over a wide range of engine speed（1...In order to evaluate the heating performance of gas engine heat pump（GEHP） for air-conditioning and hot water supply, a test facility was developed and experiments were performed over a wide range of engine speed（1400-2600 r/min）, ambient air temperature（2.4-17.8 ℃） and condenser water inlet temperature（30-50℃）. The results show that as engine speed increases from 1400 r/min to 2600 r/min, the total heating capacity and energy consumption increase by about 30% and 89%, respectively; while the heat pump coefficient of performance（COP） and system primary energy ratio（PER） decrease by 44% and 31%, respectively. With the increase of ambient air temperature from 2.4 ℃ to 17.8 ℃, the heat pump COP and system PER increase by 32% and 19%, respectively. Moreover, the heat pump COP and system PER decrease by 27% and 15%, respectively, when the condenser water inlet temperature changes from 30 ℃ to 50 ℃. So, it is obvious that the effect of engine speed on the performance is more significant than the effects of ambient air temperature and condenser water inlet temperature.展开更多
文摘目的探讨5.0 T超高场MRI中T2加权液体衰减反转恢复序列(T2-weighted fluid-attenuated inversion recovery,T2W-FLAIR)在可疑脑血管病患者脑白质高信号(white matter hyperintensities,WMH)检测中的图像质量优势及病灶可视化的价值。材料与方法前瞻性纳入2023年11月至2024年9月73例因疑似或确诊脑缺血事件患者。所有患者均接受5.0 T及3.0 T头颅MRI检查。由经验丰富的放射科医师采用Likert 5分量表法评估两种场强下T2W-FLAIR序列的图像质量,并定量计算信噪比(signal-to-noise ratio,SNR)、对比度噪声比(contrast-to-noise ratio,CNR),比较同一患者相同脑区的WMH病灶面积及数量。统计学分析采用Wilcoxon符号秩检验及配对χ^(2)检验。结果相较于3.0 T T2W-FLAIR,5.0 T T2W-FLAIR的图像质量评分(5.0 vs.4.5)、SNR(2.44 vs.1.97)、CNR(1.43 vs.0.97)更高,且WMH检出效果更好。此外,同一患者相同区域5.0 T T2W-FLAIR显示的WMH病灶面积更大(P<0.001)、数量更多(P<0.001),尤其是对微小病灶的检测能力提升显著。结论5.0 T T2W-FLAIR在WMH的显示上优于3.0 T T2W-FLAIR,尤其在图像清晰度、微小病灶检出方面更具优势,有助于脑内小缺血灶的早期诊断及准确评估,具有重要临床价值。
基金Project(hx2013-87)supported by the Qingdao Economic and Technology Development Zone Haier Water-Heater Co.Ltd.,China
文摘In order to evaluate the heating performance of gas engine heat pump（GEHP） for air-conditioning and hot water supply, a test facility was developed and experiments were performed over a wide range of engine speed（1400-2600 r/min）, ambient air temperature（2.4-17.8 ℃） and condenser water inlet temperature（30-50℃）. The results show that as engine speed increases from 1400 r/min to 2600 r/min, the total heating capacity and energy consumption increase by about 30% and 89%, respectively; while the heat pump coefficient of performance（COP） and system primary energy ratio（PER） decrease by 44% and 31%, respectively. With the increase of ambient air temperature from 2.4 ℃ to 17.8 ℃, the heat pump COP and system PER increase by 32% and 19%, respectively. Moreover, the heat pump COP and system PER decrease by 27% and 15%, respectively, when the condenser water inlet temperature changes from 30 ℃ to 50 ℃. So, it is obvious that the effect of engine speed on the performance is more significant than the effects of ambient air temperature and condenser water inlet temperature.
基金supported by the National Natural Science Foundation of China(1127301761401207+2 种基金6147119661501240)the College Graduate Scientific Research Innovation Fund in Jiangsu Province of China(KYLX16_0447)
