Passage 20 潜热与感热

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先看题：

1. The primary purpose of the passage is to discuss which of the following?

Consider each of the choices separately and select all that apply

2. According to the passage, solar-energy systems located on Earth must store energy for which of the following reasons?

Consider each of the choices separately and select all that apply

3. The author suggests that which of the following constitutes a potential disadvantage of using latent heat for energy storage?

文章讲解：

①Constant variations in the amount of sunlight available on Earth at any given location make energy storage a necessary design feature of terrestrial solar-energy systems. ②For systems transforming solar to thermal energy, the thermal energy may be stored in matter as either latent heat or sensible heat.③ Latent heat is absorbed or released whenever matter changes phase, as when matter changes from liquid to gas, for example, or from gas to liquid. ④Large heat capacities are associated with certain materials, like salts, but in any substance this storage is available only at the unique fixed temperature at which the particular phase transition occurs in that substance. ⑤Moreover, materials that have transitions at the temperatures that terrestrial solar-energy systems are likely to encounter are usually destructively corrosive at those temperatures. ⑥The storage of sensible heat, on the other hand, allows flexibility as to temperature; in addition, safe substances like water and most rocks have large sensible heat capacities.

①

↓

②

↓

③     ↔    ⑥

↓ aw-

④ + ⑤ 

 

①Constant variations in the amount of sunlight available on Earth at any given location make energy storage a necessary design feature of terrestrial solar-energy systems. ②For systems transforming solar to thermal energy, the thermal energy may be stored in matter as either latent heat or sensible heat. ③ Latent heat is absorbed or released whenever matter changes phase, as when matter changes from liquid to gas, for example, or from gas to liquid. ④Large heat capacities are associated with certain materials, like salts, but in any substance this storage is available only at the unique fixed temperature at which the particular phase transition occurs in that substance. ⑤Moreover, materials that have transitions at the temperatures that terrestrial solar-energy systems are likely to encounter are usually destructively corrosive at those temperatures. ⑥The storage of sensible heat, on the other hand, allows flexibility as to temperature; in addition, safe substances like water and most rocks have large sensible heat capacities.

1. The primary purpose of the passage is to discuss which of the following?

B

A. Reasons for the necessity for developing solar-energy systems 没有证据

B. Different ways of storing solar energy as heat 符合

C. New designs for devices that collect solar energy 没有证据

D. Procedures for transferring thermal energy between materials 没有证据

E. Differences between capacities of solids and liquids to store sensible heat. 无关，细节证据与主旨无关

 

Consider each of the choices separately and select all that apply

2. According to the passage, solar-energy systems located on Earth must store energy for which of the following reasons?

A

A. At any given location on Earth, the amount of sunlight available frequently changes. 符合

B. The operation of such systems depends on devices that require a power source other than solar energy 没有证据

C. Demand for the energy produced by such systems varies in unpredictable ways 没有证据

 

Consider each of the choices separately and select all that apply

3. The author suggests that which of the following constitutes a potential disadvantage of using latent heat for energy storage?

AC

A. The circumstances under which phase transitions occur would limit the versatility of latent heat as a storage method. 符合but in any substance this storage…

B. The supply of substances that possess the properties that are needed in a medium for latent heat storage is dwindling. 没有证据

C. The properties that are needed in a medium for latent heat storage are found in substances that have other undesirable properties. 符合Moreover, materials that have transitions…

背景拓展：

潜热，相变潜热的简称，指物质在等温等压情况下，从一个相变化到另一个相吸收或放出的热量。这是物体在固、液、气三相之间以及不同的固相之间相互转变时具有的特点之一。固、液之间的潜热称为熔解热（或凝固热），液、气之间的称为汽化热（或凝结热），而固、气之间的称为升华热（或凝华热）。

感热是指当此热量加入或移去后，会导致物质温度的变化，而不发生相变。物质的摩尔量、摩尔热容和温差三者的乘积为显热。即物体不发生化学变化或相变化时，温度升高或降低所需要的热称为显热。它能使人们有明显的冷热变化感觉，通常可用温度计测量出来。