【正文】 rature greater than the saturation temperature, it is a superheated vapor. Pressure and temperature of a superheated vapor are independent properties, because the temperature can increase while pressure remains constant. Gases such as air at room temperature and pressure are highly superheated vapors.如果一種物質(zhì)在飽和溫度和壓力的蒸氣存在，它被稱為飽和蒸氣。過熱蒸汽壓力和溫度是獨(dú)立的屬性，因?yàn)闇囟仍黾樱鴫毫Ρ３植蛔?。The second law of thermodynamics differentiates and quantifies processes that only proceed in a certain direction (irreversible) from those that are reversible. The second law may be described in several ways. One method uses the concept of entropy flow in an open system and the irreversibility associated with the process. The concept of irreversibility provides added insight into the operation of cycles. 熱力學(xué)第二定律的區(qū)別和量化，只有在某一個方向，是可逆的（不可逆）進(jìn)行的過程。一種方法是使用在一個開放的系統(tǒng)，并與進(jìn)程關(guān)聯(lián)的不可逆性的熵流的概念。The Carnot cycle, which is pletely reversible, is a perfect model for a refrigeration cycle operating between two fixed temperatures, or between two fluids at different temperatures and each with infinite heat capacity. Reversible cycles have two important properties: (1) no refrigerating cycle may have a coefficient of performance higher than that for a reversible cycle operated between the same temperature limits, and (2) all reversible cycles, when operated between the same temperature limits, have the same coefficient of performance卡諾循環(huán)，這是完全可逆的，是一個完美的模型之間的兩個固定的溫度，或在不同溫度和熱容量無限每個的兩種流體之間的制冷循環(huán)的運(yùn)行。本章介紹有關(guān)暖通空調(diào)過程的流體力學(xué)，評論相關(guān)的流程，基礎(chǔ)知識，并提出了一種單相流體流動分析的一般性討論。 gases may range from pressible to nearly inpressible. 流體與固體區(qū)別在于他們對剪切力的反應(yīng)作用。流體不同于固體剪切他們的反應(yīng)。液體和氣體都是流體。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。 most fluids in the HVAC industry (., water, air, most refrigerants) can be treated as Newtonian. In nonNewtonian fluids, the relationship between the rate of deformation and shear stress is more plicated.粘度是流體的抗剪切的措施。在牛頓流體，變形率是成正比的剪應(yīng)力。在非牛頓流體，變形和剪切應(yīng)力率之間的關(guān)系更為復(fù)雜。熱能是從一個地區(qū)轉(zhuǎn)移到另一個傳熱的三種模式：傳導(dǎo)，對流和輻射。Thermal conduction is the mechanism of heat transfer whereby energy is transported between parts of continuum by the transfer of kinetic energy between particles or groups of particles at the atomic level. In gases, conduction is caused by elastic collision of molecules。氣體中，分子的彈性碰撞引起的傳導(dǎo)。金屬的熱傳導(dǎo)時，如導(dǎo)電，通過自由電子的運(yùn)動。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]有凈物資流動的過程中，輻射是不是一個因素。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，傳熱稱為自然對流或自然對流。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，傳熱稱為自然對流或自然對流。比例系數(shù)，導(dǎo)熱系數(shù)K。電導(dǎo)率值有時在其他單位，但一致的單位，必須在使用公式1。比例系數(shù)，導(dǎo)熱系數(shù)K。電導(dǎo)率值有時在其他單位，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 terms of the humidity ratio, γ = W/(1 + W) (9b)n Absolute humidity (alternatively, water vapor density) dv is the ratio of the mass of water vapor to total volume of the sample: dv = Mw/V (10)n Density ρ of a moist air mixture is the ratio of total mass to total volume: ρ = (Mda + Mw )/V = (1/v)(1 + W) (11) where v is the moist air specific volume, m3/kgda, as defined by Equation (27).濕度比例方面，γ= W /（1+ W）（9B）絕對濕度（另外，水蒸氣密度）DV的水蒸氣的質(zhì)量樣品總量的比例：DV = MW/ V（10）潮濕的空氣混合物的密度ρ總量的比例是總質(zhì)量：ρ=（MDA+ MW）/ V =（1 / V）（1+ W）（11）其中V是潮濕的空氣中特定卷，m3/kgda，由方程（27）定義。此參數(shù)是在熱力學(xué)濕球和露點(diǎn)溫度的部分分開考慮。一個被廣泛接受的的定義是，“熱舒適性，心理狀況，與熱環(huán)境表示滿意”。The conscious mind appears to reach conclusions about thermal fort and disfort from direct temperature and moisture sensations from the skin, deep body temperatures, and the efforts necessary to regulate body temperatures. In general, fort occurs when body temperatures are held within narrow ranges, skin moisture is low, and the physiological effort of regulation is minimized.意識的頭腦似乎達(dá)到熱舒適性和不適的結(jié)論，直接從皮膚，深部體溫，以及必要的努力來調(diào)節(jié)體溫的溫度和水分的感覺。確定搬遷戰(zhàn)略和設(shè)備時，粒子和氣體之間的區(qū)別是重要的的。粒子可能是液體，固體或液體包圍了堅(jiān)實(shí)的核心。Also a central cooling and heating plant provides higher diversity and generally operates more efficiently with lower maintenance and labor costs th