Design of BYD Seal CTB cold plate

The cold plate of the Seal CTB is arranged below the cell, rather than above the cell like the Han EV or DMi.

Seal CTB is BYD blade battery integration program, the first cold plate placed at the bottom of the cell, starting from this product, the integration idea of BYD blade battery system has been adjusted, the idea and role of the battery cell participating in the whole package, the whole vehicle has changed, the assembly idea of the battery cell in the whole package has also changed, and the safety protection and electrical safety of the battery cell in the whole package have also changed.

▲Seal CTB cold plate position

The direct cold plate of the seal CTB and the profile frame of the battery pack are fixed together by the scheme of welding + fasteners, and three reinforced structural parts are arranged in the front, middle and rear positions of the cold plate.

The cold plate is composed of an upper cover plate and a lower runner plate, and the upper cover plate is a flat surface, which is bonded to the battery cell by thermal conductive structural glue; The downrunner plate mainly forms the shape of the runner, and forms a channel for the flow of cooling medium after being connected with the flat cover plate. The connection of the cover plate to the runner plate is done by brazing.

▲Structural composition of seal CTB cold plate

Due to the design of the seal CTP with a beam in the middle, the cell area is divided into two parts, so the cold plate has two heat exchange zones, the first exchange area and the second exchange area, which correspond to the cooling of the cells in the two areas. In the middle of the two heat exchange zones is the interval zone that does not have a cooling effect.

▲Flow?channel design of seal?CTB?cold plate

The role of the interval area is mainly three: (1) it does not have a cooling effect and reduces heat loss; (2) As a structural part, provide the connection and fixing of the middle position of the cold plate with the lower box body and the strengthening plate; (3) Designed to accommodate the structure/slot.

▲Holding?structure/slot of seal?CTB?cold plate

The main function of the holding groove is to hold air, because when the upper cover plate is fastened to the runner plate, the air at the spacer may not flow into the runner on both sides, or it may not flow into the space outside the runner plate and the cover. This phenomenon causes the unflowed part of the air to be closed and squeezed in the position where the two plate-like structures fit between the first heat exchange zone and the second heat exchange zone. This residual air affects the fixed connection between the cover plate and the runner plate, where the welding reliability of both is reduced. In practical applications, this structural hazard may cause the plate-like structure between the first heat exchange zone and the second heat exchange zone to be stretched open by the pressure inside the flow channel, causing leakage; Alternatively, due to the presence of air pockets, there is a risk of reduced uniformity of heat transfer performance.

The holding tank can replace the runner to hold the air that cannot be vented, and from the above figure and the actual product, the holding tank can be extended along the length of the spacer to provide the role of holding air for more space in the spacer.