英文科研论文写作技巧

[3]

摘要例

3

Abstract:

This

paper

presents

a

performance

evaluation

of

two

passive

cooling

strategies,

daytime

ventilation and night cooling, for a generic, six-story suburban apartment building in Beijing and Shanghai. The

investigation uses a coupled, transient simulation approach to model heat transfer and airflow in the apartments.

Wind-driven ventilation is simulated using computational fluid dynamics (CFD). Occupant thermal comfort is

accessed using Fanger

’

s comfort model. The results show that night cooling is superior to daytime ventilation.

Night cooling may replace air-conditioning systems for a significant part of the cooling season in Beijing, but

with a high condensation risk. For Shanghai, neither of the two passive cooling strategies can be considered

successful.

摘要例

4

ABSTRACT

:

This

paper

presents

the

results

of

a

computer

program

developed

for

solving

2-

and

3-D

ventilation problems. The program solves, in finite difference form, the steady- state conservation equations of

mass, momentum and thermal energy. Presentation of the fluctuating velocity components is made using the k-

ε

turbulence model. Predicted results of air velocity and temperature distribution in a room are corroborated by

experimental measurements. The numerical solution is extended to other room ventilation problems of practical

interest.

[4]

3.2

如何写引言

中国有句俗话：

好的开头等于成功的一半。

英文中有句名言：

“

A

bad

beginning

makes

a

bad

”

。

两者表 达方式不同，意思却相近：开头对很多事非常重要，对写文章也不例外。引言即是文章的开头。

< br>

写作之前，心中需对阅读对象有所了解和估计，这样在行文时对遣词造句就会有 把握，既避免过于

专业，使读者难以理解，又不致过于平白，让读者索然无味。

引言一般用一般现在时写，如前所述，引言中应介绍以下几方面的内容 ：

(1)

介绍讨论的问题、介绍研究的背景，说明讨论的范围及解决问题的重要性。读者往往通过浏览

论文题目、摘要、引言、图标和结论决定是否仔细阅读全文。因此，在引言中应开门见山，说

明要讨论的问题及其重要性。

(2)

相关研究回顾与综述。对已有 研究的评价要实事求是，对前人工作的精彩和可参考之处应简要

说明，对已有研究的不足 和局限，也应指出，但语气应友善而含蓄。

(3)

说明本研究的目的和特别之处 。有了前面

2

部分的铺垫，现在就要具体说明本研究要解决什么

问题，在解决思路、方法、手段等上有什么新颖或改进之处。

(4)

说明一下文章安排。是全部论 文的导读。就像领人去一个地方游览或参观，先介绍一下游览的

4

活动安排并给一张游览地的地图 。在这部分，下面的表述可供参考：

This paper is divided into five major sections as follows

…

Section one of this paper opens with

…

Section three develops the second hypothesis on

…

Section four shows (introduces, reveals, treats, develops, deals with, etc.)

…

The result of

…

is given in the last section.

(5)

介绍一下主要结论。

(4)

和

(5)

的安排比较灵活，有时可不同时出现，甚至不出现，只介绍

(3)

－本论文的目的或主要

贡献及 其重要性。

关于引言的功能，

Raleigh

N elson

有一段形象的介绍：

“

(i t)

may

be

thought

of

as

a

preliminary

conference

in

which

the

writer

and

prospective

reader

‘

go

into

a

huddle

’

and

agree

in

advance

on

the

exact

limits

of

the

subject,

the

terms

in

which

to

discuss

it,

the

angle

from

which

to

approach

it,

and

the

plan

of

treatment that will be most convenient to both.

”

引言部分逻辑性很强。 首先当然是点出问题，并使读者一下被吸引。这就必须交代为什么你选择该

问题，该问题 的解决状况如何，还有那些问题需要研究，你如何解决这些问题，得到了哪些有意义的结

果。这些环节联系紧密、环环相扣。

引言中要引用已发表的相 关文献，一般有两种引出方式：按所引文献出现的先后顺序标注，按所引

文献作者的姓名 的字母顺序标注。具体方式，视所投期刊要求而定。

下面通过一些例子对上面的介绍加以说明。

例

1

[1]

：

INTRODUCTION

A

variety

of

building

materials

(e.g.,

adhesives,

sealants,

paints,

stains,

carpets,

vinyl

flooring,

and

engineered

woods)

can

act

as

indoor

sources

of

volatile

organic

compounds

(VOCs).

Following

their

installation or application, these materials typically contain residual quantities of VOCs that are then emitted

over time. Once installed and depending upon their properties, these materials may also interact with airborne

VOCs

through

alternating

sorption

and

desorption

cycles

(Zhao

et

al.,

1999b, 2001).

Consequently,

building

materials

can

have

a

significant

impact

on

indoor

air

quality

both

as

sources

of

and

sinks

for

volatile

compounds.

Current

methods

for

characterizing

the

source/sink

behavior

of

building

materials

typically

involve

chamber studies. This approach can b time-consuming and costly, and is subject to several limitations (Little

and

Hodgson,

1996).

For

those

indoor

sources

and

sinks

that

are

controlled

by

internal

diffusion

processes,

physically-based

diffusion

models

hold

considerable

promise

for

prediction

emission

characteristics

when

compared to empirical methods (Cox et al., 2000b, 2001b).

The

key

parameters

for

physically-based

models

are

the

material/air

partition

coefficient

(K),

the

material-phase diffusion coefficient (D), and, in the case of a source, the initial concentration of VOC in the

material

(C

0

).

Rapid

and

reliable

determination

of

these

key

parameters

by

direct

measurements

or

by

estimations

based

on

readily

available

VOC/building

material

properties

should

greatly

facilitate

the

development and use of mechanistic models for characterizing the source/sink behavior of diffusion-controlled

materials (Zhao et al., 1999a; Cox et al., 2000a, 2001a).

Several procedures have been used to measure D and K of volatile compounds in building materials. D

and K have been inferred from experimental data obtained in chamber studies (Little et al., 1994). A procedure

using

a

two- compartment

chamber

has

also

been

used

for

D

and

K

measurement.

A

specimen

of

building

material

is

installed

between

the

two

compartments.

A concentration

of a

particular

compound

if

introduced

into the gas-phase of one compartment while the gas-phase concentration in the other compartment is measured

over

time.

D

and

K

are

then

indirectly

estimated

from

gas-phase

concentration

data

(Bodalal

et

al.,

2000;

5

Meininghaus et al., 2000). A complicating feature of this method is that VOC transport between chambers may

occur by gas-phase diffusion through pores in the building material in addition to solid-phase Fickian diffusion,

confounding estimates of the mass transport characteristics of the solid material.

A

procedure

based on

a European Committee

for

Standardization

(CEN)

method

has

also

been

used

to

estimate D. A building material sample is tightly fastened to the open end of a cup containing a liquid VOC. As

the VOC diffuses from the saturated gas-phase through the building material sample, cup weight over time is

recorded. Weight change data can be used to estimate D. (kirchner et al., 1999). A significant drawback of this

method

is

that

D

has

been

shown

to

become

concentration

dependent

in

polymers

at

concentrations

approaching saturation (Park et al., 1989).

In accordance with a previously proposed strategy for characterizing homogeneous, diffusion-controlled,

indoor sources and sinks (Little and Hodgson, 1996), the objectives of this study were to (1) develop a simple

and rapid experimental method for directly measuring the key equilibrium and kinetic parameters, (2) examine

the validity of several primary assumptions upon which the previously mentioned physically-based models are

founded and (3) develop correlations between the O and K, and readily available properties of VOCs.

例

2

[2]

：

1.

Introduction

Liquid

desiccant

cooling

systems

have

been

proposed

as

alternatives

to

the

conventional

vapor

compression cooling systems to control air humidity, especially in hot and humid areas. Research has shown

that a liquid desiccant cooling system can reduce the overall energy consumption, as well as shift the energy

use away from electricity and toward renewable and cheaper fuels (Oberg and Goswami, 1998a). Burns et al.

(1985) found that utilizing desiccant cooling in a supermarket reduced the energy cost of air conditioning by

60% as compared to conventional cooling. Oberg and Goswami (1998a) modeled a hybrid solar cooling system

obtaining

an

electrical

energy

savings

of

80%,

and

Chengchao

and

Ketao

(1997)

showed

by

computer

simulation that solar liquid desiccant air conditioning has advantages over vapor compression air conditioning

system in its suitability for hot and humid areas and high air flow rates.

Use of liquid desiccants offers several design and performance advantages over solid desiccants, especially

when

solar

energy

is

used

for

regeneration

(Oberg

and

Goswami,

1998c).

Several

liquid

desiccants

are

commercially

available:

triethylene

glycol,

diethylene

glycol,

ethylene

glycol,

and

brines

such

as

calcium

chloride, lithium chloride, lithium bromide, and calcium bromide which are used singly or in combination. The

usefulness of a particular liquid desiccant depends upon the application. At the University of Florida, Oberg and

Goswami (1998a,b) conducted a study of a hybrid solar liquid desiccant cooling system using triethylene glycol

(TEG) as the desiccant. Their experimental work concluded that glycol works well as a desiccant. However,

pure triethylene glycol does have a small vapor pressure which causes some of the glycol to evaporate into the

air. Although triethylene glycol in nontoxic, any evaporation into the supply air stream makes it unacceptable

for use in air conditioning of an occupied building. Therefore, there is a need to evaluate other liquid desiccants

for hybrid solar desiccant cooling systems.

Lithium chloride (LiCl) is a good candidate material since it has

good desiccant characteristics and does not vaporize in air at ambient conditions. A disadvantage with LiCl is

that it is corrosive. This paper presents an experimental and theoretical study of aqueous lithium chloride as a

desiccant for a solar hybrid cooling system, using a packed bed dehumidifier and regenerator.

A number of experimental studies have been carried out on packed bed dehumidifiers using salt solutions

as desiccants. Chung et al. (1992, 1993), and Chen et al. (1989) used lithium chloride (LiCl); Ullah et al. (1998),

Kinsara et al. (1998) and Lazzarin et al. (1999) used calcium chloride (CaCl2); while Ahmed et al. (1997) and

Patnaik et al. (1990) used lithium bromide (LiBr). Other experiments for absorbers using LiCl were carried out

by Kessling et al. (1998), Kim et al. (1997) and Scalabrin and Scaltriti (1990).

The moisture that transfers from the air to the liquid desiccant in the dehumidifier causes a dilution of the

6

desiccant

resulting

in

a

reduction

in

its

ability

to

absorb

more

water.

Therefore,

the

desiccant

must

bee

regenerated to its original concentration. The regeneration process requires heat which can be obtained from a

low temperature source, for which solar energy and waste energy from other processes are suitable. Different

ways

to

regenerate

liquid

desiccants

have

been

proposed.

Hollands

(1963)

presented

results

from

the

regeneration of lithium chloride in a solar still. Hollands focused his study on the still efficiency, concluding

that lithium chloride can be regenerated in a solar still with a daily efficiency of 5 to 20% depending on the

insolation and the concentration of the desiccant. Ahmed Khalid et al. (1998) presented an exergy analysis of a

partly

closed

solar

generator

to

compare

it

with

the

solar

collector

reported

previously.

Ahmed

et

al.

(1997)

simulated a hybrid cycle with a partly closed-open solar regenerator for regeneration the weak solution. They

found that the system COP is about 50% higher than that of a conventional vapor absorption machine. Leboeuf

and Lof (1980) presented an analysis of a lithium chloride open cycle absorption air conditioner which utilizes

a

packed

bed

for

regeneration

of

the

desiccant

solution

driven

by

solar

heated

air.

In

this

case,

the

air

temperature ranged from 65 to 96

o

C while the desiccant temperature ranged from 40 to 55

o

C. Lof et al. (1984)

conducted experimental and theoretical studies of regeneration of aqueous lithium chloride solution with solar

heated

air

in

a

packed

column.

In

this

case,

air

at

a

temperature

of

82

to

109

o

C was

used

to

regenerate

the

desiccant at an average temperature of 36

o

C.

In

any

thermodynamic

system,

the

conditions

of

the

working

fluids

and

parameters

of

the

physical

equipment define the overall performance of the system. In a liquid desiccant cooling system, variables such as

air and desiccant flow rate, air temperature and humidity, desiccant temperature and concentration are of great

interest for the performance of the dehumidifier. The mass ratio of air to desiccant solution MR=

m

air

/

m

sol

is an

important factor for absorber efficiency and system capacity. Previous studies have reported the performance of

packed bed absorbers and regenerators with MR between 1.3 and 3.3. The range of MR varies with the type of

absorber/regenerator, but in general better results are obtained for small MR.

For

simulation

purposes,

validated

models

are

required

for

modeling

the

absorber

in

a

liquid

desiccant

system. Models using lithium chloride have been descried by Khan and Martinez (1998), Ahmed et al. (1997)

and Kavasogullare et al. (1991). Due to the complexity of the dehumidification process, theoretical modeling

relies heavily upon experimental data. Oberg and Goswami (1998b) developed a model for a packed bed liquid

desiccant

air

dehumidifier

and

regenerator

with

triethylene

glycol

as

liquid

desiccant

which

was

validated

satisfactorily by the experimental data. The present study uses a modified version of the mathematical model

developed

by

Oberg

and

Goswami

to

compare

the

experimental

results

of

a

packed

bed

dehumidifier

and

regenerator using lithium chloride as a desiccant.

例

3

Introduction

The

measure

of

success

of

an

air

conditioning

system

design

is

normally

assessed

by

the

thermal

conditions provided by the system in the occupied zones of a building. Although the thermal condition of the air

supply may be finely tuned at the plant to offset the sensible and latent heat loads of the rooms, the thermal

condition in the room is ultimately determined by the method of distributing the air into the room. Fanger and

Pedersen

[1]

have

shown

that

the

thermal

comfort

in

a

room

is

not

only

affected

by

how

uniform

the

air

temperature and air velocity are in the occupied zone (the lower part of

a room to a height 2m) but also by the

turbulence intensity of the air motion and the dominant frequency of the flow fluctuations. There environmental

parameters which have profound influence on comfort, are influenced by the method used to diffuse the air into

the room. In addition to the supply air velocity and temperature, the size and position of the diffuser in the room

have a major influence on the thermal condition in the occupied zone [2].

In air distribution practice, ceilings and walls are very common surfaces which are used for diffusing the

air jet so that when this penetrates the occupied zone its velocity would have decayed substantially. Thus the

7

[4]

occurrence

of

draughts

is

minimized.

The

region

between

the

ceiling

and

the

occupied

zone

serves

as

an

entrainment region for the jet which causes a decay of the main jet velocity as a result of the increase in the

mass flow rate of the jet.

There

are

sufficient

information

and

design

guides

[3,

4]

which

may

be

applied

for

predicting

room

conditions produced by conventional air distribution methods. However, where non- conventional methods of

air supply are employed or where surface protrusions or rough surfaces are used in a wall-jet supply, the design

data is scarce. The air distribution system designer has to rely on data obtained from a physical model of the

proposed air distribution method. Modifications to these models are then made until the desired conditions are

achieved. Apart from being costly and time consuming, physical models are not always possible to construct at

full

scale.

Air

distribution

studies

for

the

design

of

atria,

theatres,

indoor

stadiums

etc.

can

only

be

feasibly

conducted with reduced scale models. However, tests carried out in a model should be made with dynamic and

thermal similarity if they are to be directly applied to the full scale. This normally requires the equality of the

Reynolds number, Re, and the Archimedes number, Ar, [5, 6] which is not possible to achieve in the model

concurrently.

The other problem which is often encountered in air distribution design is the interference to the jet from

rough surfaces and surface-mounted obstacles such as structural beams, light fittings etc. Previous studies [7, 8]

have shown that surface- mounted obstacles cause a faster decay of the jet velocity and when the distance of an

obstacle from the air supply is less than a certain value called

“

the critical distance

”

, a deflection of the jet into

the

occupied

zone

takes

place.

This

phenomenon

renders

the

air

distribution

in

the

room

ineffective

in

removing the heat load and, as a result, the thermal comfort in the occupied zone deteriorates. Here again there

is a scarcity of design data, particularly for non- isothermal air jets.

Air distribution problems, such as those discussed here, are most suitable for numerical solutions which, by

their nature, are good design optimization tools. Since most air distribution methods are unique to a particular

building a rule of thumb approach is not often a good design practice. For this reason, a mock-up evaluation has

so

far

been

the

safest

design

procedure.

Therefore,

numerical

solutions

are

most

suitable

for

air

distribution

system design as results can b readily obtained and modifications can be made as required within a short space

of time. Because of the complexity of the air flow and heat transfer processes in a room, the numerical solutions

to

these

flow

problems

use

iterative

procedures

that

require

large

computing

time

and

memory.

Therefore,

rigorous

validation

of

these

solutions

is

needed

before

they

can

be

applied

to

wide

ranging

air

distribution

problems.

In this paper a review is given of published work on numerical solutions as applied to room ventilation.

The

finite

volume

solution

procedure

which

has

been

widely

used

in

the

past

is

briefly

described

and

the

equations

used

in

the

k-

ε

turbulence

model

are

presented.

Numerical

solutions

are

given

for

two-

and

three- dimensional

flows

and,

where

possible,

comparison

is

made

with

experimental

data.

The

boundary

conditions used in these solutions are also described.

3.3

如何写论文的展开部分

(Approach),

结果和讨论

(Results and Discussion)

3.3.1

材料和方法部分

对于以实验为主的研 究论文，该部分往往位于论文展开部分的前面。

对于实验，描 述应尽可能详细。详细的程度应使别的研究者可以重复你的实验，对难以重复的实验

可评 价你的实验。

这一部分经常采用小标题，如：

subjects, apparatus, experimental design, and chemical synthesis

。

在这一部分，你应当说明：

(1)

你 所用的材料和化学药品的名称；

(2)

实验条件；

(3)

实验仪器；

(4)

实 验方法和步骤。

8

3.3.2

原理和理论模型部分

对于理论分析和 数值计算为主的研究论文，该部分往往位于论文展开部分的前面。

一般首先用数学方法描述所讨论的问题，如列出控制方程、边界条件和初始条件。为简化问题并突