Cooling system with elongated compartment indicator

A cooling system with defrost indicator, comprising:

• a cooling device having an insulated interior containment space, and
• a defrost and temperature rise indicator mounted on an interior wall of the cooling device,
• wherein the defrost and temperature rise indicator comprises:
• an elongated compartment including a first end and a second end separated by a side wall along a longitudinal axis of the elongated compartment, thereby forming a cavity including a first chamber and a second chamber that are fluidly connected through a narrow section located between the first and second chambers, wherein at least a portion of the elongated compartment is made of a first transparent material, and wherein a length of the elongated compartment is at least 5 times a width of the elongated compartment;
• a planar permeable structure selected from the group consisting of a glass frit, a wire net, a mesh, and a permeable plastic membrane, disposed at the narrow section and configured to prevent a movement of a solidified liquid from one chamber to another when the elongated compartment is vertically oriented;
• a liquid, comprising a first phase change material and a second phase change material, disposed in the cavity;
• a base to which the elongated compartment is releasably and rotatably attached, the base being configured to mount the elongated compartment to the interior wall of the cooling device, the defrost and temperature rise indicator being substantially planar in a plane parallel to the interior wall of the cooling device;
• and
• a graduation arranged on an outside surface of the elongated compartment suitable for measuring a liquid level in the elongated compartment,
• wherein the elongated compartment is configured to be rotated about a central axis orthogonal to the base, the first and second chambers being symmetric about the central axis,
• wherein the first and second chambers are symmetric to each other, and
• wherein the defrost and temperature rise indicator is configured to determine a defrost or temperature rise period for two or more temperature intervals in the insulated interior containment space of the cooling device.