JPH05149569A - Air heater and air cooler - Google Patents

Abstract

PURPOSE:To obtain an air heater and air cooler in which temperature loss is very little and energy is saved. CONSTITUTION:In an air heater which employs water as heating fluid, a controlling means is provided which is constituted of temperature meters 12 to 15, an electromotive adjusting valve 11 and a controller 18. In this instance, the controlling means 18 carries out such a control that a proportion of temperature difference between water outlet temperature and air inlet dry ball temperature to that between water inlet temperature and air outlet dry ball temperature has a prescribed value in a range from, for example, 0.7 to 1.4. Similarly, in an air cooler which employs water as cooling fluid, a controlling means is provided which carries out such a control that a proportion of temperature difference between water outlet temperature and air inlet dry ball temperature to that between water inlet temperature and air outlet dry ball temperature has a prescribed value in a range from, for example, 0.7 to 1.4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air heater for heating and an air cooler for cooling, and more particularly to an air heater for heating with water and an air cooler for cooling with water.

[0002]

2. Description of the Related Art Generally, in a conventional air heater using water as a heating fluid or an air cooler using water as a cooling fluid, the specific heat of air is about 0.24 with respect to the specific heat of water, and therefore, at the time of rating. The temperature difference between the inlet and outlet of the heater and cooler was about four times that of air compared to water. Therefore, as shown in FIG.
Under the heating conditions of, for example, water that has entered at 60 ° C. is cooled to 52 ° C. while heating the air, and air that has a dry-bulb temperature of 21 ° C. is heated by water and rises to 51 ° C.
Therefore, on the water inlet side of the heater, the temperature difference with air is only about 9 ° C., but on the water outlet side, the temperature difference with air is 31 ° C.

FIG. 5 shows another heating condition.
FIG. 5 shows the case where the inlet dry-bulb temperature of air is 21 ° C., which is the same as in FIG. 4, but the inlet temperature of hot water is only 45 ° C. Water coming in at 45 ° C. cools itself to 40 ° C. while heating the air, and air comes in at a dry-bulb temperature of 21 ° C. and is heated by water to rise to 39 ° C.
Therefore, on the water inlet side of the heater, the temperature difference from the air is 6 ° C.
The temperature difference with the air at the water outlet side is 19
It will be ℃.

Similarly, under the JIS cooling condition of FIG. 6, 7 ° C.
The incoming water is heated to 12 ° C. while cooling the air, and the incoming air at a dry-bulb temperature of 27 ° C. is cooled by the water and drops to 14.5 ° C. Therefore, on the water inlet side of the cooler, the temperature difference with the air is only about 7.5 ° C., but on the water outlet side, the temperature difference with the air is as high as 15 ° C.

[0005]

As described above, the temperature difference ΔT ₁ between the water temperature at the water inlet side of the air heater and the air cooler and the air outlet dry-bulb temperature, and the water temperature at the water outlet side,
Since the temperature difference ΔT ₂ of the air inlet dry bulb temperature is significantly different,
The temperature loss increases as described below.

In this specification, the temperature loss is given by (1−η). η is the temperature difference [Delta] T ₁ and the arithmetic mean temperature difference of the temperature difference _{ΔT 2 ΔTm 2 {ΔTm 2 =} (ΔT 1 + ΔT 2) / 2} and, logarithmic mean temperature difference? Tm ₁ of the temperature difference [Delta] T ₁ and the temperature difference [Delta] T ₂ [ ΔT
m ₁ = (ΔT ₂ −ΔT ₁ ) / {ln (ΔT ₂ / ΔT ₁ )}]
Is expressed as a ratio {η = (ΔTm ₁ / ΔTm ₂ )}.

Generally, the amount of heat exchanged by an air heat exchanger Q [kca
1 / n] is given by Q = ΔTm ₁ · A · h. Where ΔTm ₁ ; logarithmic mean temperature difference A;
Heat transfer area h; heat transfer coefficient Therefore, even if the temperature difference ΔTm ₂ is the same, if the difference between the temperature difference ΔT ₁ and the temperature difference ΔT ₂ becomes large, the logarithmic average temperature difference ΔTm ₁ becomes small, and as a result, the same. In order to obtain the heat exchange amount, the heat transfer area must be increased. FIG. 7 shows the relationship between ΔT ₂ / ΔT ₁ and η.

In FIG. 7, for example, when ΔT ₁ = ΔT ₂ , ΔTm ₁ = ΔTm ₂ and η = 1. Also, ΔT
_{If 2} is three times ΔT ₁ , then η = ΔTm ₁ / ΔTm ₂ = 0.9
1 and the temperature loss is 9%. Figure 4 above
Η = 0.89 under the heating JIS conditions shown in FIG. 2, η = 0.90 in the case shown in FIG. 2, and η = 0.96 under the cooling JIS conditions shown in FIG.

The present invention has been made in view of the above points, and an object of the present invention is to provide an air heater and an air cooler which eliminate the above problems, have a small temperature loss, and save energy.

[0010]

In order to solve the above problems, the present invention provides an air heater using water as a heating fluid, wherein the temperature difference between the water outlet temperature and the air inlet dry bulb temperature is:
It is characterized in that control means is provided for controlling the ratio of the temperature difference between the water inlet temperature and the air outlet dry-bulb temperature to a constant value between 0.7 and 1.4, for example.

In an air cooler using water as the cooling fluid, the ratio of the temperature difference between the water outlet temperature and the air inlet dry-bulb temperature to the temperature difference between the water inlet temperature and the air-outlet dry-bulb temperature is
For example, it is characterized in that a control means for controlling the value to a constant value between 0.7 and 1.4 is provided.

[0012]

According to the present invention, by constructing the air heater using water as the heating fluid and the air cooler using water as the cooling fluid as described above, the ratio of the temperature difference ΔT ₂ and the temperature difference ΔT ₁ (ΔT ₂ / ΔT ₁ ) is 0.7 ≦ ΔT ₂ / ΔT ₁ ≦ 1.4, and η is 0.99 or more as shown in FIG.
It is very energy efficient.

Furthermore, since the flow rate of water to be supplied to the load can be reduced, the pump power can be reduced and the piping can be made thin.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of a district heating system as an embodiment of the present invention. In the figure, hot water produced by a hot water producing apparatus 1 (usually a boiler or a heat pump) is pressurized by a pump 2, passes through a main pipe 3, and branches pipe 3-
1,3-2,3-3, ...
1, 5-2, 5-3, ... The hot water cooled in the heating loads 5-1, 5-2, 5-3, ... Passes through the branch pipes 4-1, 4-2, 4-3 ,. Merge and return to the hot water producing apparatus 1 again. FIG. 2 shows the heating load 5-1, 5-2, 5-3, ...
It is a figure which shows the details of -1 on behalf.

In FIG. 2, the heating load 5-1 includes an air heater 6 which uses hot water sent from the branch pipe 3-1 as a heating fluid to warm the air in the heating load 5-1. ..
The air is sucked by the fan 16 from the air inlet portion 7,
It is warmed when passing through the heat exchanger portion 17, and the air outlet portion 8
Discharged from. On the other hand, the hot water from the branch pipe 3-1 enters from the hot water inlet part 9, warms the air in the heat exchanger part 17, and cools itself, and from the hot water outlet part 10, the electric control valve 11 and the branch pipe 4-1. To leave. Also, the air inlet / outlet parts 8, 7
And the hot water inlet / outlet portions 10 and 9 respectively have temperature measuring devices 12 and
14, 15, and 13 are installed, and the output thereof is input to the control device 18.

In the above embodiment, the air inlet / outlet portions 8, 7
The temperature difference between the temperature of the hot water outlet 10 and the temperature of the dry-bulb temperature of the air inlet 10 is controlled by the controller 18 based on the outputs of the temperature measuring devices 12, 14, 15, and 13 installed in the hot water inlet and outlet parts 10 and 9, respectively. Is controlled to be 0.7 times or more and 1.4 times or less the temperature difference between the temperature of the hot water inlet 9 and the dry bulb temperature of the air outlet 8 to adjust the flow rate of the hot water. ..

By adjusting the flow rate of the hot water as described above, the heating condition of JIS shown in FIG.
As shown in, the outlet temperature of hot water is 27.3 ° C to 33.6 ° C.
Since the temperature is controlled to a certain temperature, the value of η shown in FIG. 7 becomes 0.99 or more, and the temperature loss becomes 1% or less. Further, compared to FIG. 4, in FIG. 3, the states of the air inlet / outlet portions 8 and 7 are the same, but the temperature drop of the hot water becomes 3 to 4 times, so for the heating load of the same heat quantity, the hot water quantity is Is 1/4 ~
It becomes 1/3.

Therefore, the power of the pump 2 in FIG. 1 can be reduced and the main pipes 3 and 4 can be made thin, so that the district heating shown in FIG. 1 is economical and saves resources. When the air inlet temperature changes (load fluctuation),
Control of fan 16 as well as control of hot water flow rate (air volume control)
By performing the same in the same manner, it is possible to save energy without impairing the followability (comfort) to the load fluctuation.

In the above embodiment, the air heater 6
However, it goes without saying that the air heater 6 may be a fan coil unit, an air handling unit, or the like.

Further, although the embodiment has been described only for heating, it is needless to say that the same effect can be obtained for an air cooler for cooling.

[0021]

As described above, in the air heater using water as the heating fluid and the air cooler using water as the cooling fluid according to the present invention, the difference between the water outlet temperature and the air inlet dry-bulb temperature is the water inlet. 0.7 times the difference between the temperature and the air outlet dry bulb temperature
Since it is configured so as to have a control device capable of controlling 1.4 times, the following excellent effects can be obtained.

The temperature loss of the air heater and the air cooler is 1% or less, which is very energy saving. Since the water flow rate on the load side is ¼ to ⅓ of the conventional one, the pump power can be reduced and the pipe size can be reduced, which is energy and resource saving. Since the water temperature returned from the load is low during heating and high during cooling, heat loss from the piping is reduced. When a hot water or cold water production device has a heat storage tank, the amount of heat storage per unit volume increases, and night power can be effectively used.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a district heating system using the present invention.

FIG. 2 is a diagram showing a configuration of a heating load of the present invention.

FIG. 3 is a diagram showing a heating condition of the present invention.

FIG. 4 is a diagram showing JIS heating conditions.

FIG. 5 is a diagram showing another heating condition.

FIG. 6 is a diagram showing JIS cooling conditions.

FIG. 7 is a diagram showing a relationship between ΔT ₂ / ΔT ₁ and η.

[Explanation of symbols]

 1 Hot water production device 2 Pump 3 Main pipe 3-1, 2, 3 ... Branch pipe 4-1, 2, 3 ... Branch pipe 5-1, 2, 3 ... Heating load 6 Air heater 7 Air inlet part 8 Air Outlet 9 Hot Water Inlet 10 Hot Water Outlet 11 Electric Control Valve 12, 13, 14, 15 Temperature Measuring Device 16 Fan 17 Heat Exchanger

Claims (4)

[Claims] 1. An air heater using water as a heating fluid, wherein a ratio of a temperature difference between a water outlet temperature and an air inlet dry-bulb temperature to a temperature difference between the water inlet temperature and the air outlet dry-bulb temperature is a constant value. An air heater provided with a control means for controlling the air heater. 2. The air heater according to claim 1, wherein the ratio of the temperature difference is a value between 0.7 and 1.4. 3. In an air cooler using water as a cooling fluid, the ratio of the temperature difference between the water outlet temperature and the air inlet dry-bulb temperature to the temperature difference between the water inlet temperature and the air outlet dry-bulb temperature is a constant value. An air cooler characterized in that a control means for controlling the air cooler is provided. 4. The air cooler according to claim 3, wherein the ratio of the temperature difference has a value between 0.7 and 1.4.