网友您好, 请在下方输入框内输入要搜索的题目:
题目内容
(请给出正确答案)
单选题
Scale accumulation on evaporator heat exchange surfaces ().
A
increases brine density
B
increases distillate salinity
C
reduces metal corrosion
D
reduces heat transfer
参考答案
参考解析
解析:
暂无解析
更多 “单选题Scale accumulation on evaporator heat exchange surfaces ().A increases brine densityB increases distillate salinityC reduces metal corrosionD reduces heat transfer” 相关考题
考题
CSometimes, the simplest ideas are the best. For example, to absorb heat from the sun to heat water, you need large, flat, black surfaces. One way to do that is to build those surfaces specially, on the roofs of buildings. But why go to all that trouble when cities are full of black surfaces already, in the form. of asphalt (柏油) roads?Ten years ago, this thought came into the mind of Arian de Bondt, a Dutch engineer. He finally persuaded his boss to follow it up. The result is that their building is now heated in winter and cooled in summer by a system that relies on the surface of the road outside.The heat-collector is a system of connected water pipes. Most of them run from one side of the street to the other, just under the asphalt road. Some, however, dive deep into the ground.When the street surface gets hot in summer, water pumped through the pipes picks up this heat and takes it underground through one of the diving pipes. At a depth of 100 metres lies a natural aquifer (蓄水层) into which several heat exchangers (交换器) have been built. The hot water from the street runs through these exchangers, warming the ground-water, before returning to the surface through another pipe. The aquifer is thus used as a heat store.In winter, the working system is changed slightly. Water is pumped through the heat exchangers to pick up the heat stored during summer. This water goes into the building and is used to warm the place up. After performing that task, it is pumped under the asphalt and its remaining heat keeps the road free of snow and ice.64. Which of the following is true according to the first two paragraphs?A. Arian de Bondt got his idea from his boss.B. Large, flat, black surfaces need to be built in cities.C. The Dutch engineer's system has been widely used.D. Heat can also be collected from asphalt roads.
考题
If the coolant temperature of a closed cooling water system for a diesel enginegradually increases, the trouble usually is( ).A.a broken shaft on the freshwater pumpB.an excessive accumulation of scale in the heat exchangerC.an incorrect thermostatic element operating rangeD.lube oil in the cooling water
考题
The temperature of the refrigerant in the evaporator coil depends mostly upon the ___.A.refrigerant pressure in the evaporatorB.cooling water temperature to the condenserC.heat load in the refrigerator compartmentD.solenoid valve in the liquid line
考题
第二组The only attention that heat exchanger should require is to ensure that the heat transfer surfaces remain substantially clean and the flow passages generally clear of obstruction. Indication that undue fouling is occurring is given by a progressive increase in the temperature difference between the two fluids, over a period of time, usually accompanied by a noticeable rise in pressure loss at a given flow.Fouling on the sea-water side is the most usual cause of deterioration in performance. The method of cleaning the sea water-side surfaces depends on the type of heat exchanger. With shell-and-tube heat exchangers, the removal of the header covers or, m the case of the smaller heat exchangers, the headers themselves, will provide access to the tubes. Obstructions, dirt, scale etc., can then be removed, using the tools provided by the heat exchanger manufacturer. Flushing through with fresh water is recommended before a heat exchanger is returned to service. In some applications, such as piston oil cooling, progressive fouling may take place on the outside of the tubes. Most manufactures recommend a chemical flushing pr6cess to remove this in situ~ without dismantling the heat exchanger.Plate heat exchangers may be cleaned by unclamping the stack of plates and mechanically cleaning the surface of each plate as recommended by the manufacturers. The plate seals may require replacement from time to time and here the manufacturers instructions should be closely followedBy which of the following indication, can we conclude that the lube oil-sea water heat exchanger is unduly fouled?A.the heat exchanger lube oil inlet temperature loweringB.the heat exchanger sea-water outlet pressure riseC.the heat exchanger temperature difference between lube oil and sea water increasingD.the heat exchanger pressure difference between sea water inlet and outlet decreasing
考题
According to the passage, which of the following statement is not true?A.the heat exchanging surfaces should be kept substantially cleanB.the heat exchanger flow passages should be clear of obstructionC.seals for the plate heat exchanger needs to be renewed oftenD.the cleaning process of the plate heat exchanger should be done following our experiences only
考题
The heat gained per pound of refrigerant in the evaporator is known as the ______.A.latent heat of vaporizationB.sensible heatC.refrigerating effectD.specific heat of vaporization
考题
An increase in the heat load to a refrigeration system will cause ______.A.the suction pressure to decreaseB.the suction temperature to increaseC.increased ice formation on the evaporator coilD.excessive short cycling of the compressor
考题
When compared to a high-expansion foam,a low-expansion foam will ______.A.Be dryerB.Be lighterC.Be less heat resistantD.Not cling to vertical surfaces
考题
单选题Excessive scale formation in a distilling plant may result from ().A
poor distillate qualityB
reduced evaporator capacityC
low brine concentrationD
improper vacuum regulation
考题
单选题The flash-evaporator is different with the submerged-tube evaporator in that for the former()A
Water is heated into vapor on heating surfacesB
Water is vaporized by pressure differenceC
There are no heating-transfer surfacesD
There are more heating-transfer surfaces
考题
单选题The refrigerant flows through the evaporator, where it () heat from the refrigerated space.A
extractsB
releasesC
gives noD
absorbs no
考题
单选题Improper cooling of a diesel engine cylinder liner due to the accumulation of scale deposits may cause ().A
low compression pressureB
increased piston wearC
increased cylinder lube oil consumptionD
poor contact between compression rings and liner
考题
单选题The scale trap is located between the ()A
king valve and the expansion valveB
solenoid valve and expansion valveC
evaporator and receiverD
compressor and evaporator
考题
单选题Waterside scale in a fire-tube boiler may cause ().A
increased heat transferB
fireside erosionC
high steam demandD
overheated tubes
考题
单选题The heat gained per pound of refrigerant in the evaporator is known as the().A
latent heat of vaporizationB
sensible heatC
refrigerating effectD
specific heat of vaporization
考题
单选题Less scale formation occurs in a flash evaporator than in a submerged tube evaporator because ().A
the distillate produced has greater purityB
no boiling occurs on heat transfer surfacesC
evaporation occurs at a higher rateD
the incoming feed is at a higher temperature
考题
单选题Which of the conditions listed represents the greatest effect of excess frost accumulation on the evaporator coils?()A
Keeps the refrigerated space coolerB
Reduces the efficiency of the plantC
Takes the load off the compressorD
Has no affect on the system
考题
单选题In a flash evaporator, scale as a result of higher than normal temperatures in most likely to occur in the ()A
second stage feed heaterB
saltwater feed heaterC
distillate coolerD
second stage vapor separator
考题
单选题Fins are installed on the generating tube surfaces in waste heat boilers to ().A
prevent soot fires in the exhaust systemB
prevent exhaust gas erosion of the tubesC
increase the velocity of exhaust gas flowD
increase the rate of heat transfer
考题
单选题On which of the following heated surfaces of a flash type evaporator would you be more likely to find soft scale formation?()A
Feed-water heater internal tube surfacesB
Internal distillate cooler tubesC
Flash chamber vertical surfacesD
Distilling condenser tubes
考题
单选题Scale and dirt accumulation in the waterside of a lube oil cooler will be indicated by a gradual increase in the lube oil().A
TBN numberB
viscosityC
temperatureD
foaming
考题
单选题An increase in the heat load to a refrigeration system will cause ().A
the suction pressure to decreaseB
the suction temperature to increaseC
increased ice formation on the evaporator coilD
excessive short cycling of the compressor
考题
单选题In a flash distilling unit, evaporator feed (seawater) first absorbs heat in the ().A
vapor feed heaterB
air ejector condenserC
saltwater heaterD
distillate cooler
考题
单选题Excessive alkalinity of the water in an auxiliary boiler can cause ().A
caustic embrittlement of the boiler metalB
acidic corrosion of the boiler metalC
hard scale deposits on the boiler tubesD
etching of the heat exchange surfaces
考题
单选题Sacrificial zinc anodes are used on the saltwater side of diesel engine heat exchangers to().A
reduce electrolytic action on heat exchanger metalsB
keep heat transfer surfaces shiny and cleanC
prevent rapid accumulation of marine growthD
provide a protective coating on heat exchanger surfaces
考题
填空题El Nino effect may become more frequent and fierce if enough heat could be brought to Pacific waters by the accumulation of greenhouse gases.____
热门标签
最新试卷