本文選題：節(jié)能　切入點(diǎn)：二級(jí)孔板　出處：《天津大學(xué)》2014年博士論文　論文類型：學(xué)位論文

【摘要】：我國能源形勢的嚴(yán)峻已成為不爭的事實(shí)，為了解決我國的能源問題，關(guān)鍵在于節(jié)能，節(jié)約優(yōu)先，效率為本。針對制冷行業(yè)，進(jìn)一步提高循環(huán)效率是關(guān)鍵。由于膨脹節(jié)流過程節(jié)能潛力巨大，而且作為制冷與熱泵系統(tǒng)中的研究薄弱環(huán)節(jié)，本文主要對膨脹部件進(jìn)行研究，通過理論分析、數(shù)值計(jì)算和試驗(yàn)研究相結(jié)合，從耗散型節(jié)流裝置孔板到回收型節(jié)流裝置膨脹機(jī)開展研究。 孔板是一種結(jié)構(gòu)簡單、造價(jià)低廉、并有一定控制性能的膨脹部件，可作為膨脹機(jī)在啟動(dòng)、非標(biāo)工況下工作或故障應(yīng)急的備用裝置。本文對耗散型節(jié)流裝置二級(jí)孔板進(jìn)行了相關(guān)研究。提出了二級(jí)孔板的設(shè)計(jì)方法，并設(shè)計(jì)加工了孔板樣板，通過試驗(yàn)對比分析了各樣板的節(jié)流特性。二級(jí)孔板的設(shè)計(jì)重點(diǎn)在于第二級(jí)多孔孔板，主要設(shè)計(jì)思路為通過開孔率轉(zhuǎn)化為相應(yīng)尺寸標(biāo)準(zhǔn)孔板的設(shè)計(jì)。對各樣板的試驗(yàn)結(jié)果表明，各級(jí)孔板孔徑的變化對其節(jié)流特性的影響不同；二級(jí)孔板能夠?qū)崿F(xiàn)流量調(diào)節(jié)作用，其中以第二級(jí)孔板對流量的調(diào)節(jié)作用為主。多孔孔板的設(shè)計(jì)參數(shù)為多孔孔板的設(shè)計(jì)以及節(jié)流效應(yīng)的試驗(yàn)提供了比較基礎(chǔ)，其中，疏密度和開孔率是影響多孔孔板節(jié)流效應(yīng)的主要因素。對于給出的二級(jí)孔板設(shè)計(jì)模型，第一級(jí)孔板的理論壓降與試驗(yàn)值之間的相對誤差在±15%以內(nèi)；而第二級(jí)孔板的理論壓降由于受到各種半經(jīng)驗(yàn)公式的誤差累積的影響，其與試驗(yàn)值之間的相對誤差在±30%以內(nèi)，有必要對模型進(jìn)行修正。 針對常規(guī)工質(zhì)膨脹比較大的特點(diǎn)，設(shè)計(jì)了回收型節(jié)流裝置雙轉(zhuǎn)子滾動(dòng)活塞式膨脹機(jī)，分析了膨脹機(jī)的基本結(jié)構(gòu)及工作過程，建立了膨脹機(jī)的不可逆損失模型。通過對膨脹機(jī)運(yùn)動(dòng)部件之間相對運(yùn)動(dòng)及各泄漏通道的分析，分別建立了膨脹機(jī)的流體泄漏模型與摩擦損失模型，并分析了潤滑油含量對物性的影響以及不同泄漏間隙下膨脹機(jī)的泄漏損失情況。通過對泄漏模型與摩擦損失模型的分析與模擬計(jì)算，提出了減小膨脹機(jī)不可逆損失的有效方法。根據(jù)建立的膨脹機(jī)模型，對膨脹機(jī)在不同工況下的運(yùn)行情況進(jìn)行了模擬計(jì)算。結(jié)果表明，工質(zhì)進(jìn)口壓力與干度對膨脹機(jī)效率的影響較大。在設(shè)計(jì)工況下膨脹機(jī)的理論效率為72.0%，理論輸出功為4.87kW。而膨脹機(jī)轉(zhuǎn)速為設(shè)計(jì)轉(zhuǎn)速1500rpm，進(jìn)口壓力在1.0MPa至2.0MPa范圍內(nèi)變化時(shí)，其理論輸出功在2.55~6.92kW之間，理論效率可以保持在63.4%~74.1%之間。 討論了膨脹相變過程中的亞穩(wěn)平衡狀態(tài)，定性分析了相變延遲現(xiàn)象對膨脹機(jī)性能的影響，探討了改善相變延遲現(xiàn)象的方法，討論了初始參數(shù)對膨脹相變過程的影響，并分析了快速降壓過程中汽泡的成長情況。由于制冷劑在膨脹機(jī)內(nèi)的膨脹相變過程為亞穩(wěn)平衡態(tài)的相變，為打破亞穩(wěn)平衡狀態(tài)需要足夠尺度的擾動(dòng)，初始溫度或壓力較高時(shí)將有助于這一過程的進(jìn)行。而相變延遲現(xiàn)象對膨脹機(jī)的影響存在一定閾值，只有相變延遲時(shí)間超過這一閾值時(shí)，膨脹過程才會(huì)受到比較明顯的影響。對膨脹腔內(nèi)的液體實(shí)現(xiàn)有效擾動(dòng)，將有助于改善相變延遲現(xiàn)象的發(fā)生。一旦汽核形成，膨脹過程中壓力的變化將成為促進(jìn)其成長的動(dòng)力，使相變過程快速進(jìn)行。 成功研制了雙轉(zhuǎn)子滾動(dòng)活塞式膨脹機(jī)樣機(jī)，并對其進(jìn)行了試運(yùn)轉(zhuǎn)與試驗(yàn)測試。結(jié)果表明，膨脹機(jī)在兩相進(jìn)口條件下運(yùn)轉(zhuǎn)平穩(wěn)，并輸出一定的膨脹功；同時(shí)也發(fā)現(xiàn)，轉(zhuǎn)子式膨脹機(jī)實(shí)現(xiàn)過冷液膨脹受到了一定的限制。其中膨脹機(jī)效率與回收功受進(jìn)口工質(zhì)干度的影響較大，基本隨干度的增加呈增加趨勢。同時(shí)，膨脹機(jī)的試驗(yàn)結(jié)果也驗(yàn)證了膨脹功的來源，主要以膨脹相變功為主。能實(shí)現(xiàn)膨脹機(jī)正常運(yùn)轉(zhuǎn)的進(jìn)口工質(zhì)干度最低為0.3。試驗(yàn)過程中隨進(jìn)口工質(zhì)干度由0.3增加至0.7，實(shí)現(xiàn)的膨脹機(jī)名義效率由最低0.6%可增加至超過80%。膨脹機(jī)的轉(zhuǎn)速集中在250~370rpm之間。回收的膨脹功在進(jìn)口干度約0.7時(shí)約達(dá)到1200W，而當(dāng)膨脹機(jī)進(jìn)口氣態(tài)工質(zhì)比例更高時(shí)，將可以得到更多的膨脹功。說明膨脹機(jī)的設(shè)計(jì)有成功的一面，也存在許多沒有預(yù)料到的地方，為進(jìn)一步提高膨脹機(jī)回收功，，提出了改進(jìn)方案。
[Abstract]:China's energy situation has become an indisputable fact, in order to solve the energy problem in our country, the key lies in energy conservation, conservation priority, efficiency oriented. In the refrigeration industry, to further improve the circulation efficiency is the key. The throttling process due to the expansion potential of energy saving, but also as a study of refrigeration and heat pump system in the weak link. Mainly study on the expansion of components, through theoretical analysis, numerical calculation and experimental study of a combination of machine, carried out the research from the dissipative type orifice plate throttling device to recovery type expansion throttling device.
The orifice plate is a kind of simple structure, low cost, and has a certain expansion member control performance, can be used as the expander in starting, non-standard working conditions or emergency standby equipment fault. Based on dissipative type throttling device two hole plate was studied. Put forward the design method of two hole plate. Design and plate processing model, the model of throttling characteristics are analyzed through experiments. Two design key hole plate is second orifice plate, the main design ideas through the opening rate into the corresponding size design of standard orifice plate. The experimental results of the model show that changes in levels of orifice the aperture Throttling Characteristics of different; two hole board to achieve flow control, the second orifices of flow regulation function. The design parameters for the design of the orifice plate orifice plate and throttling effect test Experience provides a basis for comparison, the density and porosity are the main factors influencing multi orifice plate throttling effect. For a level two hole plate design model is given, and the first level test between the theory of pressure drop orifice value of relative error is less than 15%; and second hole plate theory due to the cumulative effect of pressure drop the error by various semi empirical formulas, and the relative error between experimental value is less than 30%, it is necessary to revise the model.
For the conventional refrigerant expansion characteristics of relatively large, design recovery type throttling device of double rotor rolling piston expander, analyzes the basic structure and working process of the expander, a model of irreversible loss of expander. The expander between the moving parts and the relative motion of leakage channel analysis, are established. The expander fluid leakage model and friction loss model, and analyzed the influence of oil content on the physical properties and the different leakage gap expansion machine leakage loss. Through calculation and simulation analysis of leakage model and friction loss model, and puts forward some effective methods to reduce the irreversible loss of expander. The expander based on model the operation of the expander under different working conditions were simulated. The results show that the refrigerant inlet pressure and dry degree on expander efficiency in the design greatly. Under the working condition, the theoretical efficiency of the expander is 72%, the theoretical output power is 4.87kW., and the expander speed is 1500rpm of design speed. When the inlet pressure varies from 1.0MPa to 2.0MPa, the theoretical output power is between 2.55~6.92kW, and the theoretical efficiency can be kept between 63.4%~74.1%.
The expansion of metastable equilibrium state during the phase change process, the qualitative analysis of the influence of phase change delay phenomenon on the expander performance, discusses the methods to improve the phase delay phenomenon, the influence of initial parameters on the thermal expansion process are discussed, and analyze the growth of bubble rapid depressurization process. Because phase refrigerant in the expansion process of thermal expansion the machine is metastable, to break the disturbance of metastable equilibrium states need enough scale, the initial temperature or high pressure will contribute to this process. There are some phenomena and phase change delay threshold of the expander, only the phase delay time exceeds this threshold, the expansion process will be affected obviously. Effective disturbance of the fluid cavity expansion, will help improve the phase delay phenomenon. Once the nuclear steam formed during the expansion process of pressure change It will be the motive force to promote its growth and make the process of phase transition rapidly.
The successful development of the dual rotor rolling piston expander prototype, and has carried on the test run and test. The results show that the expansion machine operates smoothly in two-phase inlet conditions, and the output of the expansion work; it is also found that the rotor type expansion machine realizes the supercooled liquid expansion by a certain limit. The expander efficiency and power recovery by imported refrigerant of large dry, with dry degree increased. At the same time, the expander test results also verify the source of the expansion work, mainly by the thermal expansion of power. To achieve the normal operation of the expander imported refrigerant dryness for a minimum of 0.3. test in the process with imported refrigerant dryness increased from 0.3 to 0.7, the name of the expander efficiency can be increased to more than 0.6% of the minimum 80%. expander speed ranged from 250~370rpm. The recovery of the expansion work in the import dry degree of about 0.7 to about 1200W, and when the ratio of the inlet gaseous working medium of the expander is higher, more expansion work can be obtained. This shows that the design of the expander is successful and there are many unforeseen points. In order to further improve the recovery work of the expander, an improvement plan is put forward.

【學(xué)位授予單位】：天津大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2014
【分類號(hào)】：TB653

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