Can Cooling Towers Solve the Problem of Refrigeration Units Releasing Heat in Winter?

Can Cooling Towers Solve the Problem of Refrigeration Units Releasing Heat in Winter?
Why does this question arise?
The solution water tank is unique to the heat source tower and is used for defrosting in winter.
Working Principle
In summer, the heat source tower serves as a cold source tower, which is a direct evaporative cooling device. The cold source tower uses high-enthalpy circulating water to form a water film on the surface of the heat exchange layer, which directly makes full contact with low-enthalpy air. The partial pressure of water vapor on the surface of the high-enthalpy water film is higher than that in the low-enthalpy air, forming a pressure difference that becomes the driving force for water evaporation. The evaporation of water reduces the temperature of the circulating water, approaching the wet bulb temperature of the air, providing a cold source with a lower temperature for the water circulation refrigeration air conditioner.
In winter, the heat source tower is a device that directly collects low-grade energy outdoors. The heat source tower uses a low-enthalpy salt circulating solution to form a liquid film on the surface of the heat exchange layer, which directly makes full contact with the wet and cold air with higher enthalpy, transferring the cold energy to the air.

The temperature of the circulating liquid in contact heat transfer approaches the wet bulb temperature of the outdoor air, providing a stable heat source for the water circulation heat pump air conditioner.
Source of the Cold Source - In summer, the heat source tower evenly sprays the circulating water with a temperature higher than the wet bulb temperature of the air onto the hydrophilic filler layer of the concave-convex corrugated plates, which is N times higher than that of the cooling tower. The circulating water forms a water film on the surface of the hydrophilic filler, and the air flows in the opposite direction through the surface voids of the multi-layer concave-convex corrugated plate filler space, forming a contact surface between water and air. The water film directly exchanges sensible heat and latent heat (evaporation) with the air in a countercurrent manner. When the water evaporates, it absorbs the residual heat of the cooling circulating water of the refrigerator, reducing the temperature of the circulating cooling water and making the cooling water close to the upper limit value of 1-2°C of the wet bulb temperature of the air.
Source of the Heat Source - The antifreeze solution with a temperature lower than the wet bulb temperature is evenly sprayed onto the filler layer of the concave-convex corrugated plates with a liquid-philic property. The antifreeze solution forms a liquid film on the surface of the liquid-philic filler, and the air flows in the opposite direction through the surface voids of the multi-layer concave-convex corrugated plate filler space, forming a contact surface between the liquid and the air. The heat absorption of the solution during heat exchange in the heat source tower mainly depends on the surface liquid film, and there is both sensible heat exchange and latent heat exchange.
Sensible Heat Exchange: It is the result of heat exchange caused by conduction, convection, and radiation when there is a temperature difference between the air and the antifreeze solution.
Latent Heat Exchange: It is the result of the release (or absorption) of the latent heat of vaporization when the water vapor in the air condenses (or evaporates). The total heat exchange is the algebraic sum of the sensible heat exchange plus the latent heat (or negative latent heat) exchange, making the antifreeze solution close to the lower limit value of 1-2°C of the wet bulb temperature of the air.
Solution Concentration - During rainy days in winter at 0-4°C, while the antifreeze solution film of the heat source tower directly exchanges sensible heat and latent heat with the air, it condenses the moisture in the air, resulting in a decrease in the concentration of the antifreeze solution and an increase in the freezing point. The function of the concentration device is to concentrate the diluted antifreeze solution, lowering the freezing point.
Solution Evaporation - When the temperature difference between the dry and wet bulbs exceeds a certain value on sunny days in winter, the self-evaporation and concentration process of the antifreeze solution occurs, lowering the freezing point.
The heat source tower type water source heat pump unit is a product that uses air as the heat source and, through the heat exchange of the heat source tower and the function of the heat pump unit, realizes multiple functions such as refrigeration, ice storage, heating, and the provision of sanitary hot water.
In winter, it uses a carrier medium with a freezing point lower than zero degrees to efficiently extract the low-grade heat energy in the air with relatively high humidity in a low-temperature environment, realizing the transfer of low-temperature heat energy to high-temperature heat energy and achieving the purpose of heating;
In summer, due to the special design of the heat source tower, it acts as an efficient cooling tower, discharging heat into the atmosphere to achieve refrigeration.
It is suitable for the climatic conditions in the areas south of the Yangtze River where the calculated outdoor dry bulb temperature for winter air conditioning is not lower than -8°C and the calculated relative humidity is not lower than 60% (Suzhou -2.5°C, 77%).
This is the heat source tower heat pump system. The left side shows the operation process in summer, which is exactly the same as the mode of the chiller unit. The right side is converted into the heating working condition after the valve conversion. Please note that the inlet water temperature to the heat source tower is -3 degrees.

At this temperature, the water will freeze, so some antifreeze agents (such as methanol, ethanol, ethylene glycol, water-soluble amide, calcium chloride, sodium chloride, etc.) are added. If the external environmental temperature is too low, the concentration of the antifreeze agent will increase, the specific heat capacity of the circulating water in the heat source tower will decrease, and the heat exchange efficiency will be reduced. At the same time, due to the increase in concentration, parameters such as the viscosity and density of the solution will change to a certain extent, which will lead to an increase in the head and power of the water pump. Therefore, this system is not very suitable when the temperature is lower than -8°C.
Composition of the Heat Source Tower:
When the heat source tower is turned on, the outdoor air enters the tower from the air inlet grille 4, exchanges heat with the fins and the coil pipes, and is discharged from the air outlet cylinder 2 on the upper side. When the ambient temperature is higher than 1°C, the surface of the coil pipes will not frost, and the condensate water control device 14 is turned on to directly drain the condensate water. When the ambient temperature is lower than 1°C, the condensate water is likely to frost on the surface of the coil pipes. At this time, the spray pump 17 will be started, and the condensate water control device 14 will be closed. The concentrated solution is sent from the solution tank 16 to the sprayer 18, and the high-concentration solution is sprayed onto the coil pipes to absorb the condensate water. After being diluted, it returns to the solution tank through the solution control valve 15. The spray liquid will be blown away by the wind and diluted by the condensate water, resulting in drift loss and condensation loss. When the concentration in the solution tank is lower than a certain level, the automatic dosing device will automatically add the agent to increase its concentration. When the humidity of the outdoor air is low, the spray liquid will also have an excessively high concentration due to evaporation, and water needs to be replenished.
Tower Body:
Fan:
Heat Exchanger:
Spray Device:
Antifreeze and Water Supply System:
Closed Heat Source Tower:
The circulating medium always flows inside the pipeline and does not come into contact with the external air;
The heat exchanger is made of copper pipes and fins;
The spray device is mainly used to spray the antifreeze solution to prevent the surface of the heat exchanger from frosting and freezing;
The antifreeze solution in the spray device does not mix with the circulating medium.
Flow Chart of the Closed Heat Source Tower:
Open Heat Source Tower:
The circulating medium flows inside the pipeline, is sprayed onto the heat exchanger through the spray device in the tower, and comes into direct contact with the air;
The heat exchanger is made of filler (plastic, PVC, PP);
The spray device is mainly used to spray the circulating medium, so that the circulating medium comes into contact with the air.
Flow Chart of the Open Heat Source Tower:
Flow Chart of the Heat Source Tower Heat Pump System:
These valves are used to switch the refrigeration and heating working conditions of the heat pump unit. Small heat pump units (scroll air-cooled modules, scroll water-source and ground-source heat pumps) automatically switch between the cooling and heating conditions by switching the four-way reversing valve on the refrigerant pipeline. For large heat pump units (centrifugal, screw types), due to the large structural differences between the evaporator and the condenser, the evaporator and the condenser cannot be switched by a simple four-way reversing valve, and the working conditions in winter and summer can only be switched by adding external valves.
Single Refrigeration System Diagram:
Single Heating System Diagram:
Single Hot Water Production System Diagram: