1. Take secondary return air conditioning system of re-heater adjustable proportion, its characterized in that: the air treatment unit comprises a primary return air mixing section, a surface cooling section, a secondary return air mixing section, a reheating section and a fan section, wherein the return air pipeline is respectively connected with the primary return air mixing section and the secondary return air mixing section of the air treatment unit, the primary return air pipeline is provided with an analog quantity electric regulating valve, and the secondary return air pipeline is provided with an analog quantity electric regulating valve.

2. The air handling unit of claim 1, wherein the air handling process when the heat and humidity are relatively high in the cooling and heating condition in summer comprises the following steps: the fresh air is mixed with the indoor primary return air, cooled by the surface cooler, mixed with the indoor secondary return air to an air supply state point, and sent into the room.

3. The air handling unit of claim 1, wherein the air handling process when the heat and humidity ratio of the cooling condition in summer and the transitional season is smaller comprises: the fresh air is mixed with the indoor primary return air, cooled by a surface cooler, mixed with the indoor secondary return air, subjected to constant-humidity heating to the intersection point of the indoor heat-humidity ratio line, namely the air supply state point, and sent into the room.

Background

At present, a primary air return system is mostly adopted in the design of an air conditioning system with temperature and humidity control requirements, and when the primary air return air conditioning system controls the humidity, the air conditioning system needs to be cooled and dehumidified firstly, and then heated to an air supply state point to be sent into a room. In the process of firstly cooling and then reheating, the phenomenon of balancing cold and heat is generated, and serious energy waste is caused. The design scheme also adopts a secondary air return system design with fixed primary air return ratio and secondary air return ratio, so that the energy-saving effect is better, but the primary air quantity and the secondary air quantity cannot change along with the change of the load, and the maximized energy conservation is not realized.

The traditional secondary return air is that outdoor fresh air and part of indoor return air are mixed, then are subjected to heat and humidity treatment, and are mixed with part of indoor return air and are mixed with the return air twice, so that the secondary return air is called, and the secondary mixed air volume is used for offsetting the reheating quantity required by the primary return air, so that the purpose of energy conservation is achieved. The traditional secondary return air has no reheater, the requirement of load change is met by adjusting the primary return air and the secondary return air in operation, however, the dew point temperature is reduced when the heat-humidity ratio is reduced in the adjusting process, and the conventional cold source of 7/12 ℃ is difficult to meet the requirement of low dew point temperature, so the requirement of load change is difficult to meet by the mode, and the effective control cannot be basically adopted in actual projects.

Disclosure of Invention

The invention aims to provide a proportion-adjustable secondary return air conditioning system with a reheater, which can adjust the primary return air quantity and the secondary return air quantity according to the change of indoor load, can meet the requirement of dew point temperature by using a conventional cold source, and solves the problem that the traditional secondary return air system cannot control the low dew point.

In order to achieve the purpose, the invention provides the following technical scheme: the proportion-adjustable secondary return air conditioning system with the reheater is characterized by comprising an air handling unit 1, a service room 2, an air supply pipeline 3, a return air pipeline 4 and a fresh air pipeline 5 as shown in figure 1, wherein the air handling unit comprises a primary return air mixing section a, a surface cooling section b, a secondary return air mixing section c, a reheating section d and a fan section e, the return air pipeline is respectively connected with the primary return air mixing section and the secondary return air mixing section of the air handling unit, the primary return air pipeline is provided with an analog quantity electric regulating valve 6, and the secondary return air pipeline is provided with an analog quantity electric regulating valve 7.

The air treatment process of the air treatment unit in summer when the heat and humidity under the cold supply working condition is relatively high is as follows: the fresh air W point and the indoor primary return air N point are mixed to the point C, cooled to the point L by the surface air cooler, mixed with the indoor secondary return air N point to the air supply state point O, and sent into the room as shown in figure 2.

The air processing flow of the air processing unit when the heat humidity ratio of the cooling working condition in summer and the transitional season is smaller is as follows: the fresh air W point and the indoor primary return air N point are mixed to the point C, cooled to the point L by a surface cooler, mixed with the indoor secondary return air N point to the point M, and subjected to equal-humidity heating to the point O of the intersection point of the indoor heat-humidity ratio line, namely the air supply state point, and then sent into the room as shown in figure 3.

Its summer of foretell air treatment unit and transition season cooling operating mode heat and humidity air treatment process when relatively hour also can set up the reheater between cold section of table and secondary return air mixed section, promptly: the fresh air W point and the indoor primary return air N point are mixed to the point C, cooled to the point L by the surface air cooler, subjected to equal-humidity heating to the point M of the intersection point of the indoor heat-humidity ratio line, mixed with the indoor secondary return air to the point O of an air supply state and sent into the room, as shown in the figure 4.

The two air treatment methods with smaller heat humidity have different reheater positions and same action, the former has larger air volume passing through the reheater and better heat exchange effect, and both methods are in the protection scope of the invention.

The above-mentioned heat and humidity ratio is relatively large and relatively small means: the temperature of the intersection point L of the indoor heat-humidity ratio line and the saturated relative humidity line is T_LWhen the surface air cooler can cool the air temperature after mixing the fresh air and the primary return air to T_LThe heat and humidity are high, and when the surface air cooler can not cool the air temperature after mixing the fresh air and the primary return air to T_LThe heat and humidity are relatively small.

The air treatment process of the air treatment unit under the working condition of heat supply in winter can be designed according to the existing method, and the functional section is arranged according to the requirement. Such as a filtering section, a preheating section, a humidifying section and the like.

The functional sections of the air treatment process can be arranged in the air treatment unit in a unified way or can be arranged separately, and the protection scope of the invention is also included.

The invention is provided with a reheater, is used when the heat humidity ratio under the cold supply working condition is smaller, and aims to improve the dew point temperature and effectively control a secondary air return system. The main reason that the traditional secondary return air is not applied is that all parameters of the design method are calculated according to the maximum load of the air conditioner design, the change of the load is not considered comprehensively, in the change process of the actual project load, when the heat-humidity ratio of a using room is reduced, the intersection point of a heat-humidity ratio line and a saturated relative humidity line on an enthalpy diagram moves downwards, namely the dew point temperature is reduced, at the moment, a surface cooler using a conventional cold source can not cool to the required dew point temperature, and as the heat-humidity ratio is reduced continuously, the heat-humidity ratio line and the saturated relative humidity line can not have the intersection point, so that the traditional secondary return air system can not be controlled, the invention is provided with a reheater, when the mixed air state point cannot be superposed with the heat-humidity ratio line, the mixed air state point is heated to the heat-humidity ratio line to meet the requirement of load change, and simultaneously, a primary return air pipe and a secondary return air pipe are provided with an analog quantity electric regulating valve, the air quantity can be adjusted according to the load change, and the energy is saved to the maximum extent.

The invention provides a proportion-adjustable secondary return air conditioning system with a reheater, which has the following energy-saving effects: the phenomenon of offsetting most cold and heat of the existing primary air return air-conditioning system is avoided, the existing primary air return system with a reheater can be replaced, the cold quantity and the reheating quantity are saved under the cold supply operation condition in summer and the transition season, and the energy-saving effect is good.

Drawings

Fig. 1 is a schematic diagram of the present invention.

Figure 2 is a plot of air treatment enthalpy for a relatively high hot humidity ratio of the present invention.

Figure 3 is a psychrometric chart of air treatment with lower heat and humidity ratios according to the present invention.

Fig. 4 is a graph of the enthalpy and humidity of the air handling system with less heat and humidity before the reheater is located in the secondary return air mixing section.

Detailed Description

In order to make the technical solutions, features and effects of the present invention clearer and easier to implement, the present invention is further explained below.

The proportion-adjustable secondary return air conditioning system with the reheater is characterized by comprising an air handling unit 1, a service room 2, an air supply pipeline 3, a return air pipeline 4 and a fresh air pipeline 5 as shown in figure 1, wherein the air handling unit comprises a primary return air mixing section a, a surface cooling section b, a secondary return air mixing section c, a reheating section d and a fan section e, the return air pipeline is respectively connected with the primary return air mixing section and the secondary return air mixing section of the air handling unit, the primary return air pipeline is provided with an analog quantity electric regulating valve 6, and the secondary return air pipeline is provided with an analog quantity electric regulating valve 7.

The following illustrates embodiments of the present invention, for example, a clean air conditioning system is designed as follows: the system includes the air handling unit, service room (toilet), the blast pipe way, the return air pipeline, the new trend pipeline, air handling unit segment position sets up including the mixed wind section of the first return air of new trend, just imitate the filter segment, the cold heating section of table, the mixed section of secondary return air, the section of reheating, add the wet section, the fan section of flow equalizing, well imitate the filter segment, the air-out section, the first return air pipeline sets up analog quantity electrical control valve, the secondary return air pipeline sets up analog quantity electrical control valve, the blast pipe way end sets up high-efficient filtration supply-air outlet.

The air treatment process when the heat humidity is larger in the summer cooling working condition is as follows: the fresh air is mixed with the indoor primary return air, is subjected to primary filtering and surface cooler cooling, is mixed with the indoor secondary return air to an air supply state point, and is sent into the room after being subjected to intermediate-effect filtering and high-efficiency filtering through the fan.

The air treatment process when the heat humidity ratio of the cooling working condition in summer and the transitional season is smaller is as follows: the fresh air is mixed with the indoor primary return air, is subjected to primary filtering, surface cooler cooling, is mixed with the indoor secondary return air, is subjected to equal-humidity heating to the intersection point of the indoor heat-humidity ratio line, and is sent into the room after being subjected to intermediate-efficiency filtering and high-efficiency filtering by the fan.

The winter air treatment process comprises the following steps: the fresh air is mixed with the indoor return air, is subjected to primary filtering, heater heating, humidifier humidifying, intermediate filtering and high-efficiency filtering through a fan and then is sent into the room.

A temperature and humidity sensor is arranged in the indoor or return air main pipeline, and the opening degree of the primary and secondary return air electric valves is adjusted according to the room temperature and humidity, so that the requirement of load change is met.

The above example is a specific implementation example of the present invention, and many embodiments of the present invention are within the scope of the present invention, and all technical solutions identical or equivalent to the contents described in the claims of the present invention are within the scope of the present invention.