一、對流熱傳優(yōu)于傳導(dǎo)熱傳
動態(tài)蓄冰槽是基于對流熱傳優(yōu)于傳導(dǎo)熱傳原理,將盤管間以隔板隔成數(shù)空間室,再配以一小型循環(huán)水泵將水導(dǎo)流而上下循環(huán)于各隔板間室,或利用泵將蓄冰槽內(nèi)水從底部抽出,從頂部撒水,如此可以利用最小的動力泵(每槽約1~2HP )構(gòu)成一動態(tài)冰水循環(huán)水流,儲冰時(shí)管內(nèi)鹵水與管外冰水間形成對流傳熱,從而提高結(jié)冰均勻度。在溶冰過程由于循環(huán)水流攪動使鹵水與冰水間的靜止水曾流動起來,可有效提高換熱效率,對于溶冰效果具相當(dāng)助益,降低殘冰量,少量剩余殘冰也會浮到水面而不會卡在盤管之間,防止盤管過度凍結(jié)而,使儲冰槽儲冷容量完全發(fā)揮。以上為動態(tài)儲冰槽基本原理,亦為其優(yōu)異之特點(diǎn)。
一般蓄冰槽在盤管內(nèi)側(cè)循環(huán)鹵水,盤管外儲水結(jié)冰于管壁,由于靜止蓄冰與鹵水熱交換為傳導(dǎo)熱傳模式,因此儲冰效率不佳。在溶冰初期,鹵水管與結(jié)冰間管壁冰迅速溶冰成水后逐漸形成鹵水與冰間的靜止水層,成為熱阻抗而使溶冰效率減緩,甚至在溶冰末期雖有剩余冰量,卻無法使用的現(xiàn)象。
二、雙向溶冰速率加倍
動態(tài)蓄冰槽的另一個(gè)特點(diǎn)是在溶冰行程可以利用冰水回水動力替代冰水循環(huán)泵,使冰水可由外而內(nèi)直接溶冰供應(yīng)空調(diào),再配合鹵水自內(nèi)而外將結(jié)冰管溶冰,形成雙向溶冰故效率加倍。
1 . Convective heat exchange is better than conduction
The dynamic ice storage tank is based on the theory that the convective heat exchange is better thsn conduction . The tank has been divided to several chambers by partition and the small circular pump guide Water flow through every chamber up and down circularly , thus the dynamic circulating chilled water flow may arise from minimum power pump ( aboutl~2 HP per tank ) , and then the flow generating the convective heat exchange between inner brine and outer chilled water to raise the freezing effect in charging process . The circulating water flow will agitate steady water layer between brine and chilled water to break resistance in the discharge process of tank . This result will improve discharge effect and exert storage energy in the tank completely . For the description given above , it’s not only the basic theory but also advantage of dynamic ice storage tank .
In general , brine is circulating in the tube and storage water will be frozen on the outer . Because of the heat exchange between still ice and brine is conduction , so that effect of ice charge is poor . In the beginning of discharge , the ice where near the walt of tube is melting rapidly and then generate still water layer as thermal resistance to reduce discharge effect between brine and ice . TO make matters worse , the remanent ice can ' t be melting in the final of discharge process.
2 . Two - way melting ice caused double effect .
The returning chilled water caused power to substitute for the circulating pump is the other character of dynamic ice storage tank . The chilled wster melts ice in the outside and brine in the inside concurrently , two - way melting ice will csuse double effect .
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