【正文】 scosity is a measure of a fluid’s resistance to shear. Viscous effects are taken into account by categorizing a fluid as either Newtonian or nonNewtonian. In Newtonian fluids, the rate of deformation is directly proportional to the shearing stress。當(dāng)剪切應(yīng)力下了堅(jiān)實(shí)的變形量只有有限的，而流體的剪切變形。Fluids differ from solids in their reaction to shearing. When placed under shear stress, a solid deforms only a finite amount, whereas a fluid deforms continuously for as long as the shear is applied. Both liquids and gases are fluids. Although liquids and gases differ strongly in the nature of molecular actions, their primary mechanical differences are in the degree of pressibility and liquid formation of a free surface. In general, liquids are considered inpressible fluids。不可逆轉(zhuǎn)的概念到周期的運(yùn)作提供額外的洞察力。如在常溫常壓下空氣的氣體是高度過熱蒸汽。如果液體的溫度低于現(xiàn)有的壓力的飽和溫度，它被稱為是過冷液體（溫度低于給定壓力的飽和溫度）或壓縮液體（壓力大于飽和為給定的溫度壓力）。一個(gè)過程是指定的初始和最終的平衡狀態(tài)，路徑（如果識(shí)別），并采取跨系統(tǒng)的邊界，在這個(gè)過程中發(fā)生的相互作用。通常情況下，熱力學(xué)性質(zhì)相結(jié)合，形成其他屬性。系統(tǒng)狀態(tài)的定義是通過列出其屬性。Heat Q is the mechanism that transfers energy across the boundaries of systems with differing temperatures, always toward the lower temperature. Heat is positive when energy is added to the system. Work is the mechanism that transfers energy across the boundaries of systems with differing pressures (or force of any kind), always toward the lower pressure. If the total effect produced in the system can be reduced to the raising of a weight, then nothing but work has crossed the boundary. Work is positive when energy is removed from the system. 熱量Q與不同的溫度，跨系統(tǒng)的邊界傳輸能量總是向溫度較低的機(jī)制。 conversely, an orderly or unmixed configuration is one of low entropy. Energy has the capacity for producing an effect and can be categorized into either stored or transient forms as described in the following sections. 熵和能量的概念，在任何熱力學(xué)系統(tǒng)操作。A thermodynamic system is a region in space or a quantity of matter bounded by a closed surface. The surroundings include everything external to the system, and the system is separated from the surroundings by the system boundaries. These boundaries can be movable or fixed, real or imaginary. 一個(gè)熱力學(xué)系統(tǒng)是一個(gè)在空間或有事項(xiàng)的數(shù)量由一個(gè)封閉的表面范圍內(nèi)的區(qū)域。The concepts that operate in any thermodynamic system are entropy and energy. Entropy measures the molecular disorder of a system. The more mixed a system, the greater its entropy。能源已經(jīng)產(chǎn)生效果的能力，并在下面的章節(jié)中所述，可以存儲(chǔ)或短暫形式分類。A property of a system is any observable characteristic of the system. The state of a system is defined by listing its properties. The most mon thermodynamic properties are temperature T, pressure p, and specific volume v or density ρ. Additional thermodynamic properties include entropy, stored forms of energy, and enthalpy. Frequently, thermodynamic properties bine to form other properties. Enthalpy h, a result of bining properties, is defined as: h=u+pv where u is the internal energy per unit mass系統(tǒng)屬性是系統(tǒng)的任何觀察到的特征。一個(gè)進(jìn)程是一個(gè)狀態(tài)的改變，在系統(tǒng)屬性的任何改變，可作為定義。它可以存在于超過一個(gè)階段，但在各個(gè)階段的化學(xué)成分是一樣的If a substance is liquid at the saturation temperature and pressure, it is called a saturated liquid. If the temperature of the liquid is lower than the saturation temperature for the existing pressure, it is called either a subcooled liquid (the temperature is lower than the saturation temperature for the given pressure) or a pressed liquid (the pressure is greater than the saturation pressure for the given temperature). 如果一種物質(zhì)在飽和溫度和壓力的液體，它被稱為飽和液體。過熱蒸汽壓力和溫度是獨(dú)立的屬性，因?yàn)闇囟仍黾?，而壓力保持不變。一種方法是使用在一個(gè)開放的系統(tǒng)，并與進(jìn)程關(guān)聯(lián)的不可逆性的熵流的概念。本章介紹有關(guān)暖通空調(diào)過程的流體力學(xué)，評(píng)論相關(guān)的流程，基礎(chǔ)知識(shí)，并提出了一種單相流體流動(dòng)分析的一般性討論。流體不同于固體剪切他們的反應(yīng)。在一般來說，液體被認(rèn)為是不可壓縮的流體，氣體可能范圍從可壓縮到幾乎不可。在牛頓流體，變形率是成正比的剪應(yīng)力。熱能是從一個(gè)地區(qū)轉(zhuǎn)移到另一個(gè)傳熱的三種模式：傳導(dǎo)，對(duì)流和輻射。氣體中，分子的彈性碰撞引起的傳導(dǎo)。在堅(jiān)實(shí)的不透明機(jī)構(gòu)，熱傳導(dǎo)是顯著的傳熱機(jī)制，因?yàn)闆]有凈物資流動(dòng)的過程中，輻射是不是一個(gè)因素。如果是內(nèi)部所產(chǎn)生的溫度變化所造成的非均質(zhì)密度的流體流動(dòng)，傳熱稱為自然對(duì)流或自然對(duì)流。電導(dǎo)率值有時(shí)在其他單位，但一致的單位，必須在使用公式1。電導(dǎo)率值有時(shí)在其他單位，但一致的單位，必須在使用公式1。W = XW/ XDA（8）具體的濕度γ潮濕的空氣樣本的總質(zhì)量之比是水汽質(zhì)量：γ= MW /（MW + MDA）（9A）In