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What is the difference between open and closed dryer machines?

Views: 48     Author: Site Editor     Publish Time: 2021-08-25      Origin: Site


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The dryer machine adopts the forced hot air heated by an electric heating tube or a steam heat exchanger to circulate in the oven, which enhances heat transfer, increases the evaporation rate of water, and shortens the drying time. The whole box adopts a fully enclosed structure, and most of the hot air circulates in the box, rationally discharging hot and humid air, adding fresh air, and having high thermal efficiency and energy saving. Under the effect of forced ventilation, the material is dried evenly. Equipped with the automatic temperature control system, precise temperature control. In the dryer machine market, there are frequently heard terms such as closed dryer machine and open dryer machine, so what is the difference between them?

1. The working principle is different

2. Respective shortcomings


The working principle is different

Open-loop dryer machine

It refers to directly exhausting the hot and humid air in the drying room to the outside of the drying room through dehumidification and then replenishing natural fresh air. In fact, it can be directly understood as the direct exhaustion of moisture through the exhaust fan.

Closed-loop dryer machine

The closed-loop dryer machine can directly condense the hot and humid air in the drying room into the water and discharge it through the condensation and dehumidification device. The drying room should be relatively closed, and the air in the drying room does not contact the outside world. Completely through the refrigeration system in the drying room, the moisture in the hot and humid air is condensed into water and discharged, to achieve the purpose of reducing the air humidity in the drying room.


Respective shortcomings

(1)Disadvantages of the open dryer machine

Large heat loss due to dehumidification: The dehumidification method is adopted to remove the hot and humid air while taking away the moisture while also taking away the heat; the fresh air at room temperature will also bring the ambient humidity into the drying room;

The energy efficiency ratio is severely restricted by the ambient temperature: when the ambient temperature is lower than 15℃, the energy efficiency of the “normal” air-energy heat pump begins to decrease as the temperature decreases; when the ambient temperature is lower than 5℃, the energy efficiency of the unit will be seriously affected, and auxiliary electric heating is required.


(2)Disadvantages of the closed dryer machine

The operating conditions vary greatly: the operating conditions of the dehumidification heat pump are completely affected by the changes in the internal operating conditions of the drying room. The dry bulb temperature varies from room temperature to 80°C; the relative humidity is from <10% to >90%; the stability of the refrigeration system is complicated to control.

Without water, there is no heat: Dehumidification heat pumps rely on dehumidification to obtain steam condensation latent heat to improve heating COP, "there is no heat from the water." High temperature and low humidity, and low temperature and low humidity conditions severely restrict the energy efficiency of dehumidification heat pumps. The heating up of the material in the early stage and the maintenance of the constant temperature in the drying room in the later stage require the participation of electric heating assistance. For materials with less moisture content, air energy heat pumps with heating and dehumidification methods are more advantageous.


Sichuan Nanchong Shouchuang Technology Development Co., Ltd sincerely researches dryer machines and strives for environmental protection, energy-saving and safety. Provide customers with more valuable products.

Sichuan Nanchong Shouchuang Technology Development Co., Ltd.

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