暖通英语在线翻译Air heating (Vector AB in Figure 2) may be separated into com-ponent AC, which represents the sensible portion of the heatabsorbed by the air as the water is cooled, and component CB,which represents the latent portion. If the

暖通英语在线翻译Air heating (Vector AB in Figure 2) may be separated into com-ponent AC, which represents the sensible portion of the heatabsorbed by the air as the water is cooled, and component CB,which represents the latent portion. If the
暖通英语在线翻译
Air heating (Vector AB in Figure 2) may be separated into com-
ponent AC, which represents the sensible portion of the heat
absorbed by the air as the water is cooled, and component CB,
which represents the latent portion. If the entering air condition is
changed to Point D at the same wet-bulb temperature but at a higher
dry-bulb temperature, the total heat transfer (Vector DB) remains
the same, but the sensible and latent components change dramati-
cally. DE represents sensible cooling of air, while EB represents
latent heating as water gives up heat and mass to the air. Thus, for
the same water-cooling load, the ratio of latent to sensible heat
transfer can vary significantly.
The ratio of latent to sensible heat is important in analyzing water
usage of a cooling tower. Mass transfer (evaporation) occurs only in
the latent portion of heat transfer and is proportional to the change
in specific humidity. Because the entering air dry-bulb temperature
or relative humidity affects the latent to sensible heat transfer ratio,
it also affects the rate of evaporation. In Figure 2, the rate of evapo-
ration in Case AB (WB − WA) is less than in Case DB (WB − WD)
because the latent heat transfer (mass transfer) represents a smaller
portion of the total.
The evaporation rate at typical design conditions is approximately
1% of the water flow rate for each 7 K of water temperature range;
however, the average evaporation rate over the operating season is
less than the design rate because the sensible component of total heat
transfer increases as entering air temperature decreases.
In addition to water loss from evaporation, losses also occur
because of liquid carryover into the discharge airstream and blow-
down to maintain acceptable water quality. Both of these factors are
addressed later in this chapter.

暖通英语在线翻译Air heating (Vector AB in Figure 2) may be separated into com-ponent AC, which represents the sensible portion of the heatabsorbed by the air as the water is cooled, and component CB,which represents the latent portion. If the
空气加热（向量图2 AB公司）可分为COM的
ponent交流,代表了一部分明智的热量
以水作为冷却空气吸收和组件会CB,
它代表了潜在的部分.如果是进入空调
改为D点在同一湿球温度,但在较高
干球温度,总传热（矢量数据库）仍然
相同,但明智的和潜在的组成部分的剧作家,
卡利.明智署署长代表空气冷却,而电子束代表
潜热,水热,放弃了对空气质量.因此,
同样的水冷却负荷,潜显热比
转移有很大的差别.
对潜在的比例显热分析是很重要的水
使用的冷却塔.传质（蒸发）只发生在
潜在的传热部分,是成比例的改变
在具体的湿度.由于进入空气干球温度
或相对湿度影响潜到显热传递率,
它也影响到蒸发率.在图2中,土壤水分蒸发的速度,
在个案公司（世行 - WA）的比例是比案例数据库（世行 - 西数较少）
因为潜热转移（质）代表一个较小的
部分总额.
在典型的设计条件下蒸发率约为
1％的水每7 K表温度范围内水流量;
但是,在工作赛季平均蒸发量
低于设计速度,因为总热量合理成分
作为进入空气温度降低转移增加.
除了水的蒸发损失,损失也可能发生
由于结转到液体排放气流吹
到保持可接受的水质.这些因素都是
在本章后面讨论.