Generally, the chiller is divided into two types: air cooled chiller and water cooled chiller. It is widely used in industry fields because it can provide constant temperature, constant current and constant pressure. If the chiller is used for too long or not maintained regularly, it is inevitable that some unexpected failure will occur. Next, I will introduce you the common fault of water-cooled chiller and its solutions.
Common trouble 1: whether high and low pressure is normal
When the compressor is running with little or equal difference between high pressure and low pressure, we should check whether the valve plate of the compressor itself is damaged or broken, and immediately stop running to inform the supplier to send someone to deal with it.
Common fault 2: the indicator light up with insufficient refrigerant
When water cooled chillers’ water temperature is above 5 ℃, and temperature displayed on low pressure gauge is below 2kg/cm2, we can identify refrigerant is insufficient. At this time, we must conduct the leak detection work. If there’s any leakage point, they should be refilled immediately, then replace the drying filter and re-vacuumize, and fill the refrigerator with appropriate refrigerant.
Common fault 3: reverse phase
When this fault occurs in the water-cooled chiller, it will be timely phase protection. The cause of inverting phase is reverse of pump and compressor. At this time, we can replace any two phases in the phase line of power supply to solve this problem. If it is reverse phase, we only need to use a multimeter to measure whether the three-phase power supply is normal and check whether the power cord is broken.
Common fault 4: poor heat dissipation causes slow or unable to refrigeration
If the condenser of the water-cooled chiller has poor heat dissipation, then the compressor is inefficient, the running current will be increased, and the high-pressure will rise to 20kg/cm2. At this time, the compressor is protected by high pressure and the operation will stop. And then check whether the circulating water in the cooling tower is normal, whether the cooling water temperature is too high, whether the cooling water valve is fully open and whether the condenser is dirty, etc. And press the reset button to operate normally after all of these back to normal.
All the above tips are the common faults of water-cooled chiller and their solutions. When there’s failure in chillers , do not blindly start to maintain, otherwise will cause more serious consequences. You should seek professional personage to undertake troubleshooting.
The evaporator is used in no matter the air-cooled chiller, the air-cooled screw type chiller or the air-cooled low temperature chiller. So today we are talking about: what is an evaporator? What are the factors that affect the evaporating capacity of air-cooled chiller?
- The definition of evaporator
Evaporator is one of the four parts of the cooling system in the air-cooled chiller unit. And it’s a special part or equipment that specialize in providing liquid refrigerant to to boil and evaporate in it. Since evaporation is an endothermic process, the evaporator is the final embodiment of the refrigeration capacity and function of the air cooled chiller system. Including the indoor unit of the domestic air conditioner, its main component is evaporator. Actually, the evaporator is commonly known as an air cooler or a liquid cooler, depending on whether the object being cooled is air or liquid.
- What are the factors that affect the evaporating capacity of air-cooled chiller?
The main indexes to measure the evaporator of air-cooled chiller are heat transfer coefficient and heat transfer surface. In order to improve the efficiency of the evaporator, the heat transfer coefficient should be increased first. So the key to improve the heat transfer coefficient is to improve the convection heat transfer between the refrigerant and the heat transfer pipe wall.
Because the surface heat transfer coefficient when refrigerant boiling is far greater than that between the steam and the pipe wall. The contact surface between the liquid in the evaporator and pipe wall should be large enough, and the steam generated during boiling process shall be quickly discharged. Actually, it is difficult to increase the heat transfer coefficient.
When the heat transfer coefficient is constant, the size of heat transfer surface determines the evaporating capacity of the air-cooled chiller evaporator. Increasing the number of heat transfer pipes and using finned tubes can effectively increase the heat transfer surface, which is a common measure to improve evaporating capacity.
Refrigeration principle of air - cooled chiller
Industrial chillers can be classified into water-cooled chillers and air-cooled chillers according to refrigerating method. As far as technical level, efficiency of water-cooled chiller is 300 - 500 Kcal/h higher than air-cooled chiller. In terms of price, water-cooled chillers are much lower than air-cooled chillers. With regard to installation, the water-cooled chillers need to be incorporated into cooling towers and external pumps before they can be used. The air-cooled chillers are mobile and do not need to occupy space or any other assistance. They can only be used with power supply. But the air-cooled chiller, which dissipates heat only by fan, has some requirements for environment: such as ventilation, humidity, temperature ≦ 40 ℃, air ph, etc.