农业工程学报
農業工程學報
농업공정학보
2015年
4期
69-75
,共7页
柴油机%冷却%传热%缸盖%局部冷却%磁性纳米流%试验%节能
柴油機%冷卻%傳熱%缸蓋%跼部冷卻%磁性納米流%試驗%節能
시유궤%냉각%전열%항개%국부냉각%자성납미류%시험%절능
diesel engines%cooling%heat transfer%diesel engine cylinder head%local cooling%magnetic nanofluids%experimental%energy saving
为能实现柴油机缸盖鼻梁微区域高效冷却兼顾节能化的要求，该文提出了一种通过外部施加交变磁场的方式促进磁纳米流内粒子的微运动达到强化传热的方法，并与传统乙二醇冷却液、Cu-乙二醇纳米流冷却液进行了柴油机缸盖鼻梁微区域传热效果的对比研究。结果表明：在0.17 Hz的磁场交变频率影响下，磁纳米流中加热棒温度值最大下降幅度提升了29.3%，内部粒子运动涡数增加。缸盖鼻梁微区域试验表明：相比传统乙二醇冷却液，稳态工况下，最大扭矩工况点和标定工况点处测点温度值最大下降幅度分别约为12%、14.4%，外特性工况下测点平均温度值降幅为23.7℃，约为9.4%。瞬态工况测试结果表明，采用交变磁场影响下的磁纳米流冷却液，柴油机预热时间较采用传统乙二醇冷却液和Cu-乙二醇纳米流冷却液分别缩短了9.8%和8.2%，柴油机急加速工况下能保持冷却液温度波动性小。能耗率计算结果表明，采用外部施加交变磁场加强磁纳米流冷却液高效传热的方式在达到相同冷却液温度时，可实现节能幅度为7.2%。该研究为柴油机乃至其他高温部件的节能化高效冷却提供科学参考。
為能實現柴油機缸蓋鼻樑微區域高效冷卻兼顧節能化的要求，該文提齣瞭一種通過外部施加交變磁場的方式促進磁納米流內粒子的微運動達到彊化傳熱的方法，併與傳統乙二醇冷卻液、Cu-乙二醇納米流冷卻液進行瞭柴油機缸蓋鼻樑微區域傳熱效果的對比研究。結果錶明：在0.17 Hz的磁場交變頻率影響下，磁納米流中加熱棒溫度值最大下降幅度提升瞭29.3%，內部粒子運動渦數增加。缸蓋鼻樑微區域試驗錶明：相比傳統乙二醇冷卻液，穩態工況下，最大扭矩工況點和標定工況點處測點溫度值最大下降幅度分彆約為12%、14.4%，外特性工況下測點平均溫度值降幅為23.7℃，約為9.4%。瞬態工況測試結果錶明，採用交變磁場影響下的磁納米流冷卻液，柴油機預熱時間較採用傳統乙二醇冷卻液和Cu-乙二醇納米流冷卻液分彆縮短瞭9.8%和8.2%，柴油機急加速工況下能保持冷卻液溫度波動性小。能耗率計算結果錶明，採用外部施加交變磁場加彊磁納米流冷卻液高效傳熱的方式在達到相同冷卻液溫度時，可實現節能幅度為7.2%。該研究為柴油機迺至其他高溫部件的節能化高效冷卻提供科學參攷。
위능실현시유궤항개비량미구역고효냉각겸고절능화적요구，해문제출료일충통과외부시가교변자장적방식촉진자납미류내입자적미운동체도강화전열적방법，병여전통을이순냉각액、Cu-을이순납미류냉각액진행료시유궤항개비량미구역전열효과적대비연구。결과표명：재0.17 Hz적자장교변빈솔영향하，자납미류중가열봉온도치최대하강폭도제승료29.3%，내부입자운동와수증가。항개비량미구역시험표명：상비전통을이순냉각액，은태공황하，최대뉴구공황점화표정공황점처측점온도치최대하강폭도분별약위12%、14.4%，외특성공황하측점평균온도치강폭위23.7℃，약위9.4%。순태공황측시결과표명，채용교변자장영향하적자납미류냉각액，시유궤예열시간교채용전통을이순냉각액화Cu-을이순납미류냉각액분별축단료9.8%화8.2%，시유궤급가속공황하능보지냉각액온도파동성소。능모솔계산결과표명，채용외부시가교변자장가강자납미류냉각액고효전열적방식재체도상동냉각액온도시，가실현절능폭도위7.2%。해연구위시유궤내지기타고온부건적절능화고효냉각제공과학삼고。
Using some different ways to strength the local heat transfer ability of diesel cylinder head has some research productions, such as optimization of cooling fluid flow path, using more efficient cooling liquid, and using split cooling systems to meet demands of different positions of diesel engine. However, the effect of the first method seems limited, the results of the second method have been notoriously divergent, and the original intention of the third method is to increase intake flow. Some researchers put forward an idea that uses the nanofluids with jet impingement technology to improve the performance of heat transfer of diesel engine cylinder head, but this method has high energy consumption and cylinder head has been changed big too much. This paper attempts to use magnetic nanofluids with external alternation magnetic field to improve the heat transfer performance of diesel cylinder head at nose bridge area, based on two main reasons, one is nanofluid coolant has good heat transfer characteristics and the other is magnetic field changing enhances the nanometer particle moving trend. Based above reasons, this paper made some basic researches aiming to find out whether external alternative magnetic field can better improve moving trend of magnetic nanometer particles or not, furthermore, applying the above basic research results to a diesel with split-type cooling system to explore whether external alternative magnetic field can improve the heat transfer performance of diesel engine cylinder head or not, using traditional glycol, Cu-glycol nanofluid coolant and magnetic Fe3O4 nanofluid coolant, respectively. The results of this study showed, with the effect of external alternation at 0.17 Hz frequency, the eddy number of magnetic nanofluid coolant was increasing obviously and the heat transfer performance of nanofluid coolant was improved, and the biggest incline range of temperature value of heating rod was caused, which was 17.2%. The temperature test of cylinder head bottom showed that, compared with traditional glycol coolant, under steady operating condition, the maximum declines of the temperature values in the maximum torque point and the calibration operation point were 11.6% and 14.4%, respectively, and the average temperature decline of external characteristics operating point was 23.7℃ , around 9.4%. The testresults of transient condition showed that, compared with traditional glycol coolant or Cu-glycol nanofluid coolant, using magnetic nanofluid coolant with external alternative magnetic field at 0.17 Hz frequency, the tested diesel engine preheating time were reduced by 9.8% and 8.2%, respectively, and the coolant temperature fluctuation was relatively small. Of course, the above research results were obtained in the appropriate measures for test diesel engine. The energy consumption calculation results showed that, at the same cooling effect of test diesel engine cylinder head tiny area, compared with using traditional glycol coolant, the energy-saving rate was 7.2% when using magnetic nanofluid coolant with external alternative magnetic field at 0.17 Hz frequency. The purpose of this study is to explore the basic application method to strengthen local cooling ability on high temperature area such as diesel engine, and to provide a scientific reference of energy saving and less change for cylinder head structure.
