Find the reason w離好hy the cold storage is not c家事ooling

The common phenomenon of col村現d storage is that the temperature of th我短e cold storage cannot be lowe年業red and the temperat子議ure of the cold s服笑torage is slow.

1. The cold storage has a large loss of船湖 cooling capacity機朋 due to poor thermal insulation和湖 or sealing per吧上formance.

Poor thermal insulation 靜鐘performance is due to insufficie鐵公nt thickness of thermal insulation l業區ayers such as pipelines and空嗎 warehouse ther西黑mal insulation wa拍近lls, and poor thermal insulation 腦筆and thermal insulation effects. 家市It is mainly caused by imprope南雜r selection of therma呢土l insulation layer th動信ickness during design or poo工樂r quality of thermal insulation materia熱費ls during const視我ruction. In addition, in the 請友process of construction and u姐下se, the thermal insulation and moistur街外e-proof performance of t微但he thermal insulation material may be 技兵damaged, resulting in the therm遠風al insulation layer being damp, 來件deformed, or even 為國eroded. . Another impor拿朋tant reason for th遠制e large cooling loss is the poor se黃醫aling performance of the warehous銀我e, and more hot air i這多ntrudes into the warehouse from the 討放leak. Generally的樂, if there is condens離又ation on the sealing strip of 說睡the warehouse d數好oor or the sealing of the col人雪d storage insulation wa鄉厭ll, it means that the sealing is n服麗ot tight. In additio美亮n, frequent opening and closing of物輛 the warehouse door or more peop區中le entering the warehouse together will兒她 also increase the loss of cooling c也身apacity in the ware雜從house. Avoid opening th們關e warehouse door as much as poss房生ible to prevent a large 要畫amount of hot air刀都 from entering the warehouse. O遠拿f course, when the wa購視rehouse is freq明書uently stocked or the stock 大刀is too large, the heat志木 load increases sharply, a河玩nd it generally takes a long time 新音to cool down to the 器聽specified temperature.

2. The frost on the surface畫些 of the evaporator is to月都o thick or there is too much d門謝ust, and the heat tran和分sfer effect is reduced

Another important reason鐘也 for the slow drop of the sto冷高rage temperature is the low he弟請at transfer efficiency of the evap弟城orator, which is mainly c票體aused by the thick frost layer or湖拍 excessive dust accumulation on線農 the surface of the e近對vaporator. Since 文會the surface temperatu身又re of the evaporator in the cold 國靜storage is mostly 到還lower than 0 ℃,綠金 and the humidity in the wareh間窗ouse is relativel窗說y high, the moisture in th間如e air is easily frosted服年 or even frozen on the surface of th月老e evaporator, whic影上h affects the heat tra年睡nsfer effect of t樹那he evaporator. In order鐘友 to prevent the surfac玩路e frost layer of the evapora計行tor from being too thick, it needs 子媽to be defrosted regularly. T雪湖wo relatively simple defros見了ting methods are intro城離duced below: ① Defrosted by st答間op. That is, sto自公p the operation of the c很月ompressor, open the doo嗎樹r of the warehouse, let t光到he temperature of th厭如e warehouse rise, and restart the co高用mpressor after the fro制章st layer automat來廠ically melts. ②Defrosted by was哥哥hing. After moving the goods out 風森of the warehouse, directly rinse the 機銀surface of the evaporator問文 pipe with tap water with a higher行廠 temperature to d內腦issolve or fall off 雨如the frost layer. In addition to the她們 poor heat transfer頻業 effect of the evaporator 是弟due to the thick frost, the he暗熱at transfer efficiency of the evapo話城rator will also be sig樂黑nificantly reduced due to the excessiv門在e dust accumulation on the surface公刀 of the evaporator在看 because it has no小亮t been cleaned for a long tim都木e.

3. There is more air or refrigeratio南土n oil in the evaporator, and師為 the heat transfer effect 術我is reduced

Once more refrigerati短廠on oil is attached to the 子高inner surface of the heat transfer tu好玩be of the evaporator, its hea水知t transfer coefficient will 科中decrease. Similarly, if 們她there is more air 他自in the heat transf答外er tube, the heat transfer area of ​女子​the evaporator師家 will be reduced和妹, and its heat transfer will be reduce靜他d. Efficiency will厭業 also drop significantly,家短 and the rate of drop in ware窗習house temperature will slow down. 廠匠Therefore, in daily operati坐和on and maintenance些車, attention should be paid to timel友船y removal of oil stains on the i空亮nner surface of the evaporator hea懂少t transfer tube and discharge明了 of the air in the evaporato樂北r to improve the heat transfer ef物時ficiency of the eva和就porator.

4. The throttle valve is impr吧紙operly adjusted 木事or blocked, and the refrige市城rant flow is too large or too small

Improper adjustment or block了音age of the throttle valve wi身朋ll directly affect the flow 冷劇of refrigerant into the evaporator.農吧 When the throttle valve 舊外is opened too large, the計高 refrigerant flow rate is too larg什白e, the evaporating pressur他近e and evaporating temperatur車就e will also increase, and th照區e temperature drop rate子姐 of the warehouse will slow d制城own; at the same time, whe頻書n the throttle valve is opened too放冷 small or blocked費花, the refrigerant The flow ra麗日te is also reduced, the cooling ca醫見pacity of the system is also redu樂亮ced, and the temperature drop rate of 又土the warehouse will also slo暗器w down. Generally, it can be judged做們 whether the refrige腦器rant flow rate of the t對來hrottle valve is approp刀我riate by observing the eva吧林porating pressure, evapor樹拿ating temperature and the frosting con廠身dition of the suctio海窗n pipe. The blockage of the throt看器tle valve is an i靜城mportant factor affecting the f吧票low of refrigerant. The main reasons 報放for the blockage答數 of the throttle valve問很 are ice blockage and dirty blockag農務e. Ice blockage is due to外快 the poor dryin嗎光g effect of the dryer, and the ref輛志rigerant contain了我s moisture. When it flows thr拍店ough the thrott舞笑le valve, the temperature drops見錯 below 0 °C, and the moisture i媽作n the refrigerant freezes into ic術請e and blocks the th靜話rottle valve hole; dirty blocka去體ge is Due to the accumulation of數是 more dirt on the filter screen at 雜有the inlet of the th得請rottle valve, the flow of動商 refrigerant is not smooth, r能農esulting in blockage.

5. The amount of refri作嗎gerant in the syst歌說em is insufficient, and the co黑藍oling capacity is ins小術ufficient

There are two main reasons for insuff術人icient refrigerant 廠刀circulation. First秒學, the refrigerant 遠南charge is insufficient. At this ti南森me, only a sufficient amount of 科雪refrigerant needs to be added. Anoth兵會er reason is that there火用 are many refrigerant明什 leaks in the system. In this ca科務se, you should first find the leak 大對point, focus on check秒長ing the connections of eac習科h pipeline and valve, and the樹廠n fill in a suffi動朋cient amount of refrigerant aft坐多er repairing the lea志報ked parts.

6. The compressor effic生錯iency is low, and the coolin近體g capacity cannot meet the warehouse 朋妹load requirements

Due to the long-term operation of the吃是 compressor, the cy姐民linder liner and piston ring and other 數我components are seriously綠跳 worn, and the matching cleara和我nce increases, the sealing performa件空nce will decrease according綠南ly, the gas transmission coef文話ficient of the compressor wil年市l also decrease, and the cooling capac去也ity will decrease. When行知 the cooling capacity is less than the照信 heat load of the warehouse微坐, the temperature of the wa懂道rehouse will drop slowly. The refr了亮igeration capac和行ity of the compressor 分就can be roughly judged 唱白by observing the suction and discharge說技 pressures of the compressor. I空些f the refrigeratio自錯n capacity of the長什 compressor decreases畫技, the commonly u樹森sed method is to replace the c坐機ylinder liner and piston ring工見 of the compressor慢紅. If the replacemen金可t still does not work, othe志習r factors should暗和 be considered, or even dis店街mantling and overhauling, and troub書讀leshooting.

Problems in configuring combined門些 cold storage equipment

Combined cold s那我torage is a kind of fast a物技nd simple refrigeration equipment deve跳樹loped in recent years. It is作木 professionally 年兵produced and prefabricat討樂ed in various b厭信uilding components and heat insu城理lation panels by specializ和個ed factories, and then assemble都科d on the construc也廠tion site. At present, most of th會火e small combined cold sto業通rages can be disassemble通公d for a second time. Briefly in相南troduce the categories 了事of active cold storage:

Outdoor movable cold stora家有ge: Large, medium and small制科 combined cold storage林間s are generally男刀 designed for outdoor 朋花type. Different from indoo電路r type, outdoor type ne關土eds to be covered with outer protective訊他 structure and foundation. The 弟森outer structure 河月is wind, rain and煙錢 sun protection.

Indoor mobile cold stora城白ge: a small combined cold stora錯銀ge built in an existing 一河building.

This paper analyzes the reasonable你做 configuration of the e車海vaporator and refrigeration un分問it of the combined cold stora有秒ge equipment.

1. The configuration of the evapor讀雪ator evaporation are文放a of ​​the combined cold stor得樹age equipment is unreasona愛在ble:

There is a big gap between習舊 the evaporation are少一a of ​​the evaporato子秒r in the combined c弟章old storage and t白你he actual technical re但讀quirements of the r東區efrigeration proces高海s. According to the field observation音司 of some combined 問農cold storages, the evaporation area of 坐問​​the evaporator is聽山 only about 75% of 紙相the one that should be configured. We k聽木now that for the confi姐體guration of the ev也短aporator in the c冷錢ombined cold storage, various 飛現heat loads should be ca鐵請lculated according to its design temp他為erature requirements, and the evapo在光ration area of ​校電​the evaporator should be determine唱黃d, and then conf醫東igured according to the refrig線裡eration process requirements. If the e到也vaporator is not properly 還白configured according to th中間e design requir生些ements and the 分暗configuration area of ​​the evaporator 鐵河is blindly reduced, the refrigeration 要相coefficient per unit area of ​​th西女e evaporator of the combi數校ned cold storage w志朋ill be greatly reduced, the c吧來ooling load will increase, and 器商the energy efficiency 錢林ratio will be signifi書紙cantly reduced, r中房esulting in a combined cold sto個業rage. The internal temperature d友都rops slowly, the w火長orking coefficient of th謝見e refrigerator is rising, and th資請e operating cost increases. Theref術爸ore, when designing 女少and selecting the evaporator 商生of the combined cold storage, 計懂the area of ​​the e見風vaporator should be近校 selected according to the opt海綠imal heat transf器船er temperature difference. .

2. The configuration of th體慢e refrigeration unit 問紅of the active cold storage eq日音uipment is unreasonable:

The refrigerati著店on units configured on the co票遠mbined cold storage prod關有uced by some manufacturer爸吃s are not reaso為鄉nably configured according t內照o the total cooling l的黑oad calculated by the library design 照劇and the thickne遠著ss of the thermal銀的 insulation layer拍這 of the combined co風友ld storage envelope, but are equip科些ped with additional refrigerati厭鐵on units. The number of明空 units can be used to meet 外外the requirements畫我 of rapid cooling in the war醫我ehouse. Taking the BZL-3×4 又暗type movable cold st離視orage as an exa外近mple, the storage is樹嗎 4 meters long, 3 meters wide, 2.7 m都農eters high, and h光東as a net volume of 28.723 cubic mete空紅rs. It is equipped with tw裡輛o 2F6.3 series 腦放refrigeration units and two indepe著熱ndent groups. Serpentine light亮說 tube evaporator, each unit and an 去黃independent evapo媽制rator form a complete refrigeration開地 system for refrigeration opera有學tion. According 靜請to the estimation and analysis of t兵唱he machine load of the c匠門old storage, it can be seen 司妹that the machine load of 現雨the active cold storage is a文下bout 140 (W/m3), and老公 the actual total lo長請ad is 4021.22 (W) (3458.25 kcal).吧下 According to the above data, one 2中白F6. 3 series refrigeration units (st服你andard refrigerating cap場短acity 4000kcal/h) can al兵月so meet the refrigeration 我但process requirements of the active跳有 cold storage (up t技睡o -15℃～-18℃), therefore, it is superfl討生uous to add one more refrigerat人民ion unit to the warehous都離e, and It will 這白also increase the maintenance cos麗開t of the unit.

As we all know, in the refriger們照ation system, th微文e evaporating temp跳醫erature and the evaporating pressu視低re have a functional rela公說tionship with each other. The她到y are related to several conditions s河可uch as the temperat上廠ure of the object to be cooled, the coo有微ling capacity, the heat 答有exchange area (mainly the area of家土 ​​the evaporator) an可樂d the capacity of就照 the compressor. If one of these煙在 conditions changes, the eva金煙porating temperature and ev去風aporating pressure of the refrig內家eration system will change accordin計道gly. In the BZL-3×4 type combine那議d cold storage, t著訊he evaporation area has not changed, bu海少t the capacity 子家of the refrigerator has doubl行訊ed, which makes the evaporation c能間apacity of the evaporator of the mo笑離vable cold storage incompati街河ble with the suction capacity of t內計he compressor. (The evapor化頻ation volume Vo is much s村爸maller than the suction 水銀volume Vh of the compresso作離r), that is, V0 < Vh, the evaporat會日ion pressure Po and the evaporat那就ion temperature to drop sha從我rply, the heat transfer tempera唱做ture difference爸那 Δt increases, and it 山對is difficult to cool dow他冷n in the active cold stora慢制ge. If it is low, the performance inde快又x of the compressor will be redu線都ced, and the eco土年nomic index will 城那be deteriorated.