空間熱控蒸發(fā)器流動沸騰傳熱特性研究
發(fā)布時間：2018-10-19 16:42
【摘要】：熱控系統(tǒng),是保證航天器內溫度穩(wěn)定,各儀器設備穩(wěn)定工作的重要組成部分。隨著航天技術的不斷發(fā)展,航天器的熱控環(huán)境愈加惡劣。一方面,在輻射散熱效率低的航天器熱控系統(tǒng)中,需要使用蒸發(fā)器作為消耗性熱沉來進行熱量排散；另一方面,在低溫的環(huán)境中,又需要對關鍵設施進行加熱控溫。在任何蒸發(fā)換熱器的結構設計之中,管內兩相流流動沸騰傳熱,都是首要的考慮因素之一。本文從26篇文獻中,收集了2783個環(huán)形流流型下的流動沸騰換熱系數(shù)實驗數(shù)據(jù),建立了環(huán)形流流動沸騰換熱數(shù)據(jù)庫。該數(shù)據(jù)庫包含七種不同工質,覆蓋水力直徑范圍0.5-14.0mm,質量流速范圍50-1290kg/m2s,全液雷諾數(shù)范圍240～55119,熱力學干度范圍0.013～0.985,熱流密度范圍3.0-240.0kW/m2,液相普朗特數(shù)范圍1.26～5.85,對比壓力0.01-0.77。此外,本文總結了19種現(xiàn)有流動沸騰換熱系數(shù)預測方法,使用所建立數(shù)據(jù)庫對其進行了精度評估,發(fā)現(xiàn)大部分現(xiàn)有的方法,并不能對數(shù)據(jù)庫內數(shù)據(jù)給出令人滿意的預測精度。因此,本文基于Cioncolini-Thome環(huán)形流湍流模型,提出了一個新的換熱關聯(lián)式,用于環(huán)形流流型下的流動沸騰換熱系數(shù)計算；新關聯(lián)式的預測精度明顯高于所有現(xiàn)有模型,其MAE和MRE分別為13.7%和0.4%,預測誤差不超過±15%、±30%和±50%的數(shù)據(jù)比例分別為66.5%、89.0%和96.9%；同時,新的關聯(lián)式適用性強,對于不同工質和管道尺寸的換熱系數(shù)均能給出精度較高的預測。另一方面,本文還針對Q型槽道管內表面結構對流動沸騰傳熱特性的影響,設計并搭建了兩相流流動沸騰傳熱實驗平臺,對槽道管內流動沸騰換熱特性,以及重力方向對其傳熱特性的影響,進行了實驗研究。研究表明,管道內表面的槽道結構,能夠明顯強化核態(tài)沸騰換熱的能力,提高傳熱性能：在水平流動及豎直上升流動中,槽道管內流動沸騰換熱系數(shù)約為光滑圓管的1.5-3倍,在豎直下降流動中,最高可以達到光滑圓管8倍左右。然而,不同流動方向的流動沸騰換熱特性明顯不同,說明在實驗參數(shù)范圍內,管內槽道群結構并不能影響到兩相流流型,保證液體工質對槽道的潤濕,也不能起到消除重力影響的作用。此外,本文還針對低溫環(huán)境下航天器的加熱控溫,制備了一系居里溫度符合電子設備熱控要求的PTC材料,并從理論和實驗兩個方面,研究了利用PTC材料進行自適應控溫的適用條件和熱控特性。
[Abstract]:Thermal control system is an important part to ensure the stability of spacecraft temperature and equipment. With the development of spaceflight technology, the thermal control environment of spacecraft becomes worse and worse. On the one hand, in the spacecraft thermal control system with low radiative heat dissipation efficiency, the evaporator is used as the expendable heat sink for heat emission; on the other hand, in the low temperature environment, the key facilities need to be heated to control the temperature. In the structural design of any evaporative heat exchanger, the boiling heat transfer of two-phase flow in the tube is one of the most important factors. In this paper, the experimental data of flow boiling heat transfer coefficient under 2783 annular flow patterns were collected from 26 literatures, and a database of annular flow boiling heat transfer was established. The database contains seven different working fluids, covering the hydraulic diameter range of 0.5-14.0mm, the mass flow rate range of 50-1290kg / m ~ 2 s, the whole liquid Reynolds number range 240 ~ 55119, the thermodynamic dryness range 0.013 ~ 0.985, the heat flux range 3.0-240.0kW / m ~ (2), the liquid phase Plantt number range 1.265.85, and the relative pressure 0.01-0.77. In addition, 19 existing prediction methods of flow boiling heat transfer coefficient are summarized in this paper. The accuracy of these methods is evaluated by using the established database. It is found that most of the existing methods can not give satisfactory prediction accuracy for the data in the database. Therefore, based on the Cioncolini-Thome annular flow turbulence model, a new heat transfer correlation is proposed, which can be used to calculate the boiling heat transfer coefficient of the annular flow, and the prediction accuracy of the new correlation is obviously higher than that of all the existing models. The MAE and MRE are 13. 7% and 0. 4, respectively. The ratio of prediction error to 鹵15, 鹵30% and 鹵50% is 66.589% and 96.9%, respectively. At the same time, the new correlation has strong applicability, and the heat transfer coefficient of different working fluids and pipe sizes can be predicted with high accuracy. On the other hand, aiming at the influence of the surface structure of Q channel tube on the flow boiling heat transfer characteristics, the experimental platform of two phase flow boiling heat transfer is designed and built, and the flow boiling heat transfer characteristics in the channel tube are analyzed. The influence of the direction of gravity on the heat transfer characteristics is studied experimentally. The results show that the channel structure on the inner surface of the pipe can obviously enhance the heat transfer ability of nucleate boiling and improve the heat transfer performance. In horizontal flow and vertical upward flow, the boiling heat transfer coefficient of the flow in the channel is about 1.5-3 times that of the smooth tube. In vertical descending flow, the maximum is about 8 times of smooth circular tube. However, the flow boiling heat transfer characteristics in different flow directions are obviously different, which indicates that in the range of experimental parameters, the structure of the channel group in the tube can not affect the two-phase flow pattern and ensure the wettability of the liquid working fluid to the channel. Nor can it play a role in eliminating the effects of gravity. In addition, a series of PTC materials with Curie temperature in accordance with the thermal control requirements of electronic equipment have been prepared for spacecraft heating and temperature control in low temperature environment. The suitable conditions and thermal control characteristics of adaptive temperature control using PTC materials are studied.
【學位授予單位】：中國科學技術大學
【學位級別】：碩士
【學位授予年份】：2016
【分類號】：V444.36
本文編號：2281727
[Abstract]:Thermal control system is an important part to ensure the stability of spacecraft temperature and equipment. With the development of spaceflight technology, the thermal control environment of spacecraft becomes worse and worse. On the one hand, in the spacecraft thermal control system with low radiative heat dissipation efficiency, the evaporator is used as the expendable heat sink for heat emission; on the other hand, in the low temperature environment, the key facilities need to be heated to control the temperature. In the structural design of any evaporative heat exchanger, the boiling heat transfer of two-phase flow in the tube is one of the most important factors. In this paper, the experimental data of flow boiling heat transfer coefficient under 2783 annular flow patterns were collected from 26 literatures, and a database of annular flow boiling heat transfer was established. The database contains seven different working fluids, covering the hydraulic diameter range of 0.5-14.0mm, the mass flow rate range of 50-1290kg / m ~ 2 s, the whole liquid Reynolds number range 240 ~ 55119, the thermodynamic dryness range 0.013 ~ 0.985, the heat flux range 3.0-240.0kW / m ~ (2), the liquid phase Plantt number range 1.265.85, and the relative pressure 0.01-0.77. In addition, 19 existing prediction methods of flow boiling heat transfer coefficient are summarized in this paper. The accuracy of these methods is evaluated by using the established database. It is found that most of the existing methods can not give satisfactory prediction accuracy for the data in the database. Therefore, based on the Cioncolini-Thome annular flow turbulence model, a new heat transfer correlation is proposed, which can be used to calculate the boiling heat transfer coefficient of the annular flow, and the prediction accuracy of the new correlation is obviously higher than that of all the existing models. The MAE and MRE are 13. 7% and 0. 4, respectively. The ratio of prediction error to 鹵15, 鹵30% and 鹵50% is 66.589% and 96.9%, respectively. At the same time, the new correlation has strong applicability, and the heat transfer coefficient of different working fluids and pipe sizes can be predicted with high accuracy. On the other hand, aiming at the influence of the surface structure of Q channel tube on the flow boiling heat transfer characteristics, the experimental platform of two phase flow boiling heat transfer is designed and built, and the flow boiling heat transfer characteristics in the channel tube are analyzed. The influence of the direction of gravity on the heat transfer characteristics is studied experimentally. The results show that the channel structure on the inner surface of the pipe can obviously enhance the heat transfer ability of nucleate boiling and improve the heat transfer performance. In horizontal flow and vertical upward flow, the boiling heat transfer coefficient of the flow in the channel is about 1.5-3 times that of the smooth tube. In vertical descending flow, the maximum is about 8 times of smooth circular tube. However, the flow boiling heat transfer characteristics in different flow directions are obviously different, which indicates that in the range of experimental parameters, the structure of the channel group in the tube can not affect the two-phase flow pattern and ensure the wettability of the liquid working fluid to the channel. Nor can it play a role in eliminating the effects of gravity. In addition, a series of PTC materials with Curie temperature in accordance with the thermal control requirements of electronic equipment have been prepared for spacecraft heating and temperature control in low temperature environment. The suitable conditions and thermal control characteristics of adaptive temperature control using PTC materials are studied.
【學位授予單位】：中國科學技術大學
【學位級別】：碩士
【學位授予年份】：2016
【分類號】：V444.36
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