Rectangular dry type shell-and-tube heat exchanger

Abstract

The invention relates to a rectangular dry type shell-and-tube heat exchanger. The rectangular dry type shell-and-tube heat exchanger comprises a tube pass and a broken-line-shaped shell pass, whereinthe tube pass is composed of a channel and U-shaped heat exchange tubes, and the broken-line-shaped shell pass is composed of a shell, a tube sheet and spoilers; a tube pass inlet and a tube pass outlet are formed in the channel; and a shell pass inlet and a shell pass outlet are formed in the shell. The rectangular dry type shell-and-tube heat exchanger is characterized in that the shell is a rectangular shell; one end of the shell is closed; the tube sheet is arranged at the other end surface of the shell; the multiple U-shaped heat exchange tubes are arranged in the shell in a rectangularmode; the end parts of the U-shaped heat exchange tubes are supported by the tube sheet; the channel is arranged on the outer side of the tube sheet and is used for performing shunting on the U-shapedheat exchange tubes; and a rectangular sealing gasket is arranged between the channel and the tube sheet.

Description

technical field [0001] The invention belongs to the technical field of refrigeration (heat pump) air conditioners and low-temperature (freezing) units, and in particular relates to a new structure of a dry shell-and-tube heat exchanger. Background technique [0002] Dry-type evaporator, as the name implies, dry-type evaporator is a tube side where gas-liquid two-phase refrigerant enters the evaporator directly controlled by capillary tube, orifice plate, thermal expansion valve or electronic expansion valve, and the refrigerant liquid is completely transformed into gas in the tube. , while the cooled (heated) medium flows in the shell side outside the heat exchange tube. The shell side is equipped with a spoiler, which is used to change the fluid flow direction. It is often used in the design of the shell side medium flow channel in the dry evaporator, which can not only improve the heat transfer effect, but also play the role of supporting the tube bundle. Determine the nu...

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Problems solved by technology

[0004] Tube side: circular tube box has a large height difference △h between the highest point and the lowest point of the liquid supply distribution chamber, so the static pressure difference △p of the liquid column in the chamber is relatively large, and the gas-liquid two-phase refrigerant entering the chamber ( The gaseous refrigerant has a low density and is separated upwards; the liquid refrigerant has a high density and is separated downwards) Due to the large static pressure difference △p of the liquid column in the cavity, the gas-liquid stratification phenomenon is intensified, resulting in uneven distribution of the liquid supply. The heat exchange tube distributes mostly gaseous refrigerant, the proportion of refrigerant distributed is small and the heat exchange area is large, resulting in a waste of heat exchange area; the lower heat exchange tube distributes mostly liquid refrigerant, and the proportion of refrigerant distributed is large and The heat transfer area is small, resulting in insufficient heat transfer area and incomplete evaporation of the refrigerant, which eventually leads to the suction of the compressor with liquid

[0005] Shell side: the circular shell leads to the circular distribution of tubes on the spoiler, the tube-row spacing S on the central axis of the shell is relatively large, the flow rate of the brine is low, and the tube-row spacing S on the edge of the shell is small. The high flow rate of the brine brings three adverse effects:

[0006] 1. The heat transfer capacity of the heat exchange tube at the center of the shell and the heat exchange tube at the edge of the shell is inconsistent due to the difference in the flow rate of the refrigerant outside the tube;

[0007] 2. If the flow rate V of the brine at the center of the shell is guaranteed, the flow rate V of the brine at the edge of the shell is too high, which will cause a large impact on the heat exchange tubes at the edge of the shell and generate a large alternating stress load , affecting (shortening) the life of the heat exchange tube at the edge of the shell;

[0008] 3. If the flow rate V of the brine at the edge of the shell is guaranteed, the flow rate V of the brine in the center of the shell is too low, resulting in a decrease in the heat transfer coefficient of the water side in the center of the shell

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