Using the pressure difference between the condensation pressure and the evaporation pressure as the driving force, the high-pressure liquid is directly supplied to the evaporator for refrigeration after being throttled and depressurized, which is called direct expansion liquid supply. In cold storage devices, it is the earliest and simplest method of liquid supply, consisting of a regulating station and an evaporator. Its working principle is that the high-pressure liquid from the high reservoir is throttled and depressurized by the throttle valve on the liquid regulating station, and then sent to each group of evaporators. In the evaporators, it absorbs heat and evaporates into gas, which is then directly sent to the compressor intake through the gas regulating station.
The advantages of this liquid supply system are:
① Utilizes the energy of high-pressure liquid, reduces reactive power loss, and no other power is consumed except for the compressor;
② A compressor can be used to bear several evaporation temperatures, which is difficult for other systems to achieve;
③ Due to the lack of equipment, simple system, and low refrigerant charge in the cold storage, the price of the cold storage is low, and the primary investment is lower than that of other systems.
Air cooling is a cooling method that uses air as a medium to cool objects that need to be cooled. Usually, it is to increase the surface area of the object that needs to be cooled, or to accelerate the rate of air flowing through the object per unit time, or to share the two methods. The former can be achieved by adding a heat sink to the surface of an object, usually hanging the heat sink outside the object or fixing it to the object to make heat dissipation more efficient. The latter can use fans (fans) to enhance ventilation and cooling effects. In most cases, adding heat sinks can greatly improve cooling efficiency.
Cold and heat recovery features:
① "One machine with multiple uses can provide indoor cooling/thermal air conditioning, as well as provide domestic hot water 24/7 without climate change, which not only saves the investment and operating costs of hot water boilers, but also avoids the dependence of solar water heaters on climate.".
② Energy conservation and environmental protection: The use of a heat recovery device can recover the condensing heat of the unit to produce hot water, which not only saves energy consumption, but also avoids the thermal pollution caused by the discharge of condensed waste heat into the air and the greenhouse effect caused by carbon dioxide generated by boiler combustion.
③ Space saving: The hot water supply device of the heat recovery unit is generally built into the unit, without providing any additional installation space for the heating equipment.
The working operation of a semiconductor refrigeration sheet is using direct current, which can be used for both cooling and heating. By changing the polarity of the direct current, it is determined to achieve cooling or heating on the same refrigeration sheet. This effect is generated through the principle of thermoelectricity, which is a single piece of refrigeration sheet consisting of two ceramic sheets, with N-type and P-type semiconductor materials (bismuth telluride) between them, This semiconductor element is connected in series on the circuit The working principle of a semiconductor cooling sheet is: When a piece of N-type semiconductor material and a piece of P-type semiconductor material are connected into an electrical couple, after applying a direct current in this circuit, energy transfer can occur. The current flows from the N-type element to the joint of the P-type element to absorb heat, and the cold end flows from the P-type element to the joint of the N-type element to release heat, becoming the hot end. The magnitude of heat absorption and release is determined by the magnitude of the current and the component pairs of semiconductor materials N and P. The inside of the cooling sheet is a thermoelectric stack composed of hundreds of pairs of electric couples to enhance the cooling (heating) effect.
