提出了一种可改善换热效率的百叶窗式纵翅片换热管的结构模型,对其进行简化,采用Fluent软件对换热管烟气侧流动与传热过程进行数值模拟,对比了两种百叶窗纵翅片与普通纵翅片的换热效率与压降,结果发现:百叶窗式纵翅片传热效果比普通纵翅片高130%以上。模拟了6组不同流体入口速度下传热与压降的变化情况,分析了百叶窗翅片间距与倾斜角度对传热与压降的影响,结果表明:入口速度越大,进出口温差越小,压降越大;翅片间距越大,进出口温差和压降都越小;翅片倾斜角度越大,换热效果相差不大,压降越大。搭建了简易实验平台对模拟结果进行验证。

Longitudinal finned tube heat exchanger is a new type of tube heat exchanger used in flue gas heat recovery. In order to improve the heat transfer efficiency,the structural model of a new type of longitudinal louvered fin tubes was proposed and simplified. Using Fluent Software,the process of flow and heat transfer in gas phase was simulated for the longitudinal louver fined heat exchangers,and the transfer efficiency and pressure drop of two types of longitudinal louver fin and the common type exchanger were compared. The results showed that the heat transfer efficiency of longitudinal louvered fin heat transfer were over 130% higher than that of the common type. This paper simulates the changes of transfer and pressure drop at six different inlet velocities,and analyzed the influences of heat transfer and pressure drop caused by the difference of spacing and inclination angles on longitudinal louver fin. The results showed that at higher inlet velocities, the range of temperature was

熔盐是一种高效传热工质,广泛应用于太阳能热发电传热、核反应堆传热、金属热处理的工业过程中。以配制的一种混合硝酸熔盐作为热管的传热工质,设计制造了管壳为316L不锈钢、外径Φ22 mm、壁厚2 mm、管壳长度980 mm的硝酸熔盐重力热管,并对硝酸熔盐重力热管的启动性能进行了初步实验研究,分析了混合硝酸盐重力热管的启动特性、稳定性以及倾角对热管启动的影响。然后将采用40 g混合硝酸盐工质的重力热管实验结果与采用40 g萘工质的重力热管的实验结果进行了对比。实验结果表明,混合硝酸盐热管的启动时间比萘热管的时间短,且启动后稳定性高于萘热管;分析认为,该混合硝酸盐的沸点在250℃左右,在倾角为50°时热管启动性能优于在30°、70°、90°时的情况。实验结果初步证明了混合硝酸盐作为热管工质的可行性。

Molten salt is a highly efficient heat transfer working fluid. It is widely used in central solar power, nuclear reactor, and heat treatment of metals. The startup process of gravity heat pipe with mixed nitrate as the working fluid was investigated experimentally by analyzing the startup characteristics, stability, and the influence of inclination angle on the startup behavior. The gravity heat pipe was fabricated with 316 L stainless steel, with outer diameter of 22 mm, thickness of 2 mm and total length of 980 mm. In order to explore the heat pipe start-up behavior of mixed nitrates, the experimental result with 40 g mixed nitrate working fluid is compared to that with 40 g naphthalene working fluid. The startup time of heat pipe with mixed nitrates is shorter than that with naphthalene and the heat pipe with mixed nitrates is superior to that with naphthalene in the stability. The boiling point of mixed nitrate is about 250℃. The startup characteristics at inclination an

从热管的吸液芯对传热性能的影响出发,分别对以铜材泡沫金属和丝网为吸液芯的热管进行了传热性能试验研究,两种热管的工质都为质量浓度为1%的Al2O3纳米流体.试验结果显示泡沫金属吸液芯热管在等温性、换热系数和传热极限等方面都要比丝网吸液芯热管更好,泡沫金属吸液芯热管的传热性能要优于丝网吸液芯热管.

In order to investigate the influence of the wick on the heat transfer performance , two groups of experi-ments on heat transfer performance were conducted by using different wicks , i.e., the foam metal wick and the screen wick, both of which used Al2O3nanofluid as working medium whose mass concentration was 1%wt.Ex-perimental results show that the foam metal wick heat pipe has an advantage over the screen wick heat pipe in the aspects of isothermal , heat transfer coefficient , heat transfer limit , etc.The heat transfer performance of foam metal wick heat pipe is better than the screen wick heat pipe .

从集热器结构、传热效率、工艺、优缺点等方面详细介绍了3种常见的热管平板式太阳能集热器，它们包括蜂窝热管平板式、真空玻璃盖板热管平板式、CPC热管平板式太阳能集热器。与普通热管平板式集热器相比，3种改良方式均可降低集热器热损失，有效提高集热效率。通过对不同种类热管平板式太阳能集热器的热管种类、工作温度、结构参数等分析，发现随着温度升高，集热器集热效率下降，以及热管蒸发段长度普遍大于冷凝段长度等现象。

Three common heat pipe flat-plate solar collectors are introduced in details from the con-figuration of the collector such as heat transfer efficiency, crafts, merits, and so on, including the flat plate solar collector of honeycomb and heat pipe(HHCHP), flat plate solar collector of vacuum glass-cover board and heat pipe(HVGHP) and a compound parabolic concentrator heat pipe type solar collector(CPC). Com-pared with common heat pipe flat-plate solar collectors, these three improved programs can reduce heat loss, and effectively improve efficiency of the collector. From the analysis of different heat pipe types, oper-ating temperature, structure parameters, a phenomenon is discovered that whatever which type of heat pipe flat-plate solar collector is, as temperature goes up, the efficiency of the collectors drops and the length of evaporation is longer than the length of condensation.

为保证空间堆的传热安全，空间堆热管必须工作在各种传热极限以下，并能满足避免单点失效的安全要求。本文建立了空间堆热管黏性极限、声速极限、携带极限、沸腾极限和毛细极限5种传热极限计算方法，并改进了毛细极限计算模型。利用建立的方法计算了分段式热电偶转换的热管冷却空间堆电源系统堆芯锂热管、辐射散热器钾热管和碱金属热电转换的空间堆电源系统堆芯钠热管的传热极限。结果表明，空间堆用锂热管和钠热管的毛细极限分别为25.21 kW和14.69 kW ，钾热管的声速极限为7.88 kW ，其传热设计冗余量分别大于19.4％、23.6％和43.2％。空间堆堆芯热管在正常运行时限制其热量输出的传热极限为毛细极限，而限制散热器钾热管正常运行时热量输出的传热极限为声速极限。

To insure the safety of space reactor power system with no single point fail‐ures ,the reactor heat pipes must work below its heat transfer limits ,thus when some pipes fail ,the reactor could still be adequately cooled by neighbor heat pipes .Methods to analyze the reactor heat pipe’s heat transfer limits were presented ,and that for the prevailing capillary limit analysis was improved .The calculation was made on the lithi‐um heat pipe in core of heat pipes segmented thermoelectric module converter (HP‐STMC) space reactor power system (SRPS ) ,potassium heat pipe as radiator of HP‐STMC SRPS ,and sodium heat pipe in core of scalable AMTEC integrated reactor space power system (SAIRS) .It is shown that the prevailing capillary limits of the reactor lithium heat pipe and sodium heat pipe is 25.21 kW and 14.69 kW ,providing a design margin > 19.4% and > 23.6% ,respectively . The sonic limit of the reactor radiator potassium heat pipe is 7.88 kW ,providing a design margin >