Musamman zafi na konewar kananzir

Babban halayen thermophysical na kananzir

Kerosene shine tsakiyar distillate na aikin tace man fetur, wanda aka bayyana a matsayin adadin danyen mai da ke tafasa tsakanin 145 zuwa 300 ° C. Ana iya samun kananzir ta hanyar narkar da ɗanyen mai (kananzir mai sarrafa kai tsaye) ko kuma ta fashe magudanan ruwa masu nauyi (fasasshen kananzir).

Danyen kananzir yana da kaddarorin da suka sa ya dace da haɗawa tare da abubuwan ƙari daban-daban waɗanda ke ƙayyade amfani da shi a cikin aikace-aikacen kasuwanci iri-iri, gami da mai na sufuri. Kerosene wani hadadden hadadden hadaddun mahadi ne masu rassa da madaidaiciya wanda galibi ana iya kasu kashi uku: paraffins (55,2% ta nauyi), naphthenes (40,9%) da aromatics (3,9%).

Don yin tasiri, duk nau'ikan kananzir dole ne su kasance suna da mafi girman yuwuwar takamaiman zafin konewa da takamaiman ƙarfin zafi, sannan kuma su kasance da siffa da kewayon yanayin zafi mai faɗi. Ga ƙungiyoyi daban-daban na kananzir, waɗannan alamun sune:

• Musamman zafi na konewa, kJ / kg - 43000 ± 1000.
• autoignition zafin jiki, ⁰C, ba kasa da -215 ba.
• Ƙayyadadden ƙarfin zafi na kananzir a zafin jiki, J / kg K - 2000 ... 2020.

Ba shi yiwuwa a tantance mafi yawan ma'auni na thermophysical na kerosene, tun da samfurin kanta ba shi da wani nau'in sinadarai na yau da kullum kuma an ƙaddara shi ta hanyar halayen asali na man fetur. Bugu da kari, yawa da danko na kananzir ya dogara da yanayin zafi na waje. An sani kawai yayin da zafin jiki ya kusanci yankin kwanciyar hankali na konewar samfurin mai, takamaiman ƙarfin zafi na kananzir yana ƙaruwa sosai: a 200.⁰Tare da shi ya riga ya kasance 2900 J / kg K, kuma a 270⁰C - 3260 J/kg. Dangane da haka, dankon kinematic yana raguwa. Haɗin waɗannan sigogi yana ƙayyade mai kyau da kwanciyar hankali na kerosene.

Jerin tantance takamaiman zafin konewa

Ƙimar ƙayyadaddun calorific na kananzir ya tsara yanayin ƙonewa a cikin na'urori daban-daban - daga injuna zuwa na'urorin yankan kananzir. A cikin shari'ar farko, ya kamata a ƙayyade mafi kyawun haɗin ma'aunin thermophysical a hankali. Yawancin lokaci ana saita jadawali don kowane haɗin mai. Ana iya amfani da waɗannan ginshiƙi don kimantawa:

1. Mafi kyawun rabo na cakuda samfuran konewa.
2. Yanayin adiabatic na harshen wuta.
3. Matsakaicin nauyin kwayoyin halitta na samfuran konewa.
4. Takaitaccen rabon zafi na samfuran konewa.

Ana buƙatar wannan bayanai don tantance saurin iskar gas ɗin da ke fitowa daga injin, wanda hakan ke ƙayyade motsin injin ɗin.

Matsakaicin cakuda man fetur mafi kyau yana ba da mafi girman ƙayyadaddun kuzarin kuzari kuma aiki ne na matsin lamba wanda injin zai yi aiki. Injin da ke da babban matsi na ɗakin konewa da ƙarancin shaye-shaye zai sami mafi girman ma'aunin gauraya. Bi da bi, matsa lamba a cikin ɗakin konewa da ƙarfin kuzarin man kananzir sun dogara ne akan ma'auni mafi kyaun cakuda.

A mafi yawan kayayyaki na injuna ta amfani da kananzir a matsayin man fetur, an biya hankali sosai ga yanayin matsa lamba adiabatic, lokacin da matsa lamba da ƙarar da ke tattare da cakuda mai ƙonewa suna cikin dangantaka akai-akai - wannan yana rinjayar dorewar abubuwan injin. A wannan yanayin, kamar yadda aka sani, babu wani musayar zafi na waje, wanda ke ƙayyade iyakar yadda ya dace.

Ƙaƙƙarfan ƙarfin zafi na kananzir shine adadin zafin da ake buƙata don ɗaga zafin gram ɗaya na abu da ma'aunin Celsius ɗaya. Ƙayyadaddun ƙayyadaddun zafi na musamman shine rabo na ƙayyadaddun zafi a matsa lamba zuwa ƙayyadaddun zafi a ƙarar ƙima. An saita mafi kyawun rabo a ƙayyadadden matsa lamba mai a cikin ɗakin konewa.

Ba a kafa ainihin alamun zafi a lokacin konewar kananzir ba, tunda wannan samfurin mai cakuda ne na hydrocarbons hudu: dodecane (C).₁₂H₂₆tridecane (C₁₃H₂₈tetradecane (C₁₄H₃₀da kuma pentadecane (C₁₅H₃₂). Ko da a cikin nau'in nau'in mai na asali, adadin kaso na abubuwan da aka lissafa ba akai ba ne. Sabili da haka, ana ƙididdige halayen thermophysical na kananzir tare da sanannun sassauƙa da zato.