1. The air-cooled chiller uses copper tubes and aluminum fins to dissipate heat from the condenser. A fan is required to blow the outdoor air through the heat exchange fins and take away the heat of the condenser, so the air-cooled chiller does not need to be connected to the cooling tower. But compared with water-cooled chillers, under the same power, air-cooled chillers have larger equipment size and higher noise. The condenser of water-cooled chillers exchanges heat with the cooling water from the cooling tower through the heat exchanger. The excess waste heat will be transported to the cooling tower through the cooling water loop and released into the atmosphere, or enter the water-water heat exchanger or soil heat exchange coil for storage. Therefore, water-cooled chillers do not need fans to dissipate heat, but need cooling towers or water (ground) source heat exchange pipelines. Water-cooled chillers have one more cooling water system than air-cooled chillers. The size of the unit of the same power is smaller than that of the air-cooled chiller, it does not take up space, and the noise is lower, but it needs a cooling tower and the equipment needs a computer room.

2. In terms of refrigeration and heat exchange switching, the air-cooled chiller-type refrigerant loop switches the flow direction through a four-way valve to exchange the condenser and the evaporator. In summer, heat is transferred from indoor to outdoor, and in winter, it absorbs heat from outdoor. indoor. The water-cooled chiller does not have the ability of evaporator and condenser interchangeability, so the unit connected to the cooling tower does not have the heating function (requires an external boiler). The heat pump unit needs to switch the chilled water and cooling water loops, and 8 water circuit switching valves are added in the machine room. In summer, cold water enters the house, hot water enters the external coil, and winter hot water enters the house, and cold water enters the external coil. (Some small water source heat pump units also have refrigerant four-way valves)

3. In the case of the same cooling capacity, the model of water-cooled chiller is smaller, because the energy efficiency ratio of water-cooled chiller is higher than that of air-cooled chiller, and the compressor of air-cooled chiller is better than water-cooled chiller. Great horsepower.

4. In terms of installation, the air-cooled chiller is easy to install, while the installation pipeline of the water-cooled chiller is more complicated.

If you don’t know whether to choose an air-cooled chiller or a water-cooled chiller when choosing a chiller, you can contact us. We will recommend to you a suitable chiller based on your on-site installation, the budget of the chiller, and the size of the model. Email: oumal@oumal.com

The evaporator is one of the main components of industrial chillers. The types of evaporators include: tank with coil evaporator, shell and tube evaporator, stainless steel plate heat exchanger, titanium tube evaporator. With so many types of evaporators, how should we choose the appropriate type of evaporator for our chiller?

Water tank coil evaporator: The evaporator is a coil type structure placed in the water tank. The coil-type evaporator of Omar Refrigeration is made as follows: According to the size of the chiller required by the customer, the copper pipes are coiled in a circle, and then the coil-type evaporator is put into the built-in water tank of the box-type chiller. In this way, the refrigerant in the copper pipe can absorb the heat of the water. The water tank coil evaporator is relatively simple to manufacture. The cost is relatively low. Generally, small water chillers use water tank coil type evaporators.

Shell and tube evaporator: Shell and tube evaporator is the most widely used in screw chillers, and different materials can be selected according to different water quality requirements. For example, the middle tube can be 316 stainless steel or copper tube, or nickel white copper, and the outer shell can be carbon steel or 316 stainless steel. The shell and tube evaporator has compact structure, convenient operation and management, and high heat transfer coefficient. The disadvantage is that the refrigerant charge is large, and when the evaporation temperature is lower than 0 degrees, it is easy to freeze and damage the evaporation tube.

Stainless steel plate heat exchanger: As one of the commonly used heat exchange equipment in heat exchangers, stainless steel plate heat exchangers have certain advantages. They can be used in food, heating, domestic hot water, waste heat recovery and other fields. The data displayed by the heat exchange equipment shows that the stainless steel plate heat exchanger has a better heat exchange effect than carbon steel, and it also prolongs the service life. Stainless steel plate heat exchangers are generally divided into 316L and 304 materials. 304 stainless steel plate heat exchanger has a wide range of uses, such as corrosion resistance, heat resistance, mechanical properties, and low temperature strength. The use temperature can be (-196℃-800℃). When customers of general chillers have requirements for water quality, we will generally equip chillers with stainless steel plate heat exchangers in the choice of evaporator.

Titanium tube evaporator: The titanium tube is light in weight, high in strength, and superior in mechanical properties. When the chiller is used with corrosive liquids, such as acidic liquids, we need to use a titanium tube evaporator. For example, in the electroplating industry, the electroplating solution is highly corrosive. If the chiller directly cools the electroplating solution, a titanium tube evaporator is required. , Titanium tube evaporator is also commonly used in fish pond chillers.

After reading the main features and uses of various evaporators, do you know how to choose the right evaporator type for your chiller? If you don’t know, please contact us and tell us where your chiller is used and the type of liquid that needs to be cooled. Oumal‘s professional engineers will choose the most suitable evaporator for your water chiller systems.

(1) How to choose the most suitable industrial chiller and screw chiller? In fact, there is a simple selection formula:

Cooling capacity = chilled water flow * 4.187 * temperature difference * coefficient

1. The flow rate of chilled water refers to the flow rate of chilled water required when the machine is working, and the unit needs to be converted into liters/second;

2. The temperature difference refers to the temperature difference between the water in and out of the machine;

3. 4.187 is quantitative (specific heat capacity of water);

4. When choosing an air-cooled chiller, multiply the coefficient by 1.3, and when choosing a water-cooled chiller, multiply it by 1.1;

5. Select the corresponding machine model according to the calculated cooling capacity.

It is generally customary to use HP to calculate how much the chiller needs to be equipped, but the most important thing is to know the rated cooling capacity. Generally, the air-cooled cooling capacity is 9.07KW and the 3HP chiller is selected, and so on. Therefore, the most important thing in the selection of industrial chillers is to obtain the rated cooling capacity.

(2) The calculation method of the cooling capacity of the chiller

How to calculate the cooling capacity of the chiller

1. Volume (liter) X number of temperature rise / heating time (minute) X 60 / 0.86 (coefficient) = (W)

2. Volume (tons or cubic meters) X number of temperature rise / heating time / 0.86 (coefficient) = (KW)

(3) Selection method of chiller

Energy conservation law Q=W in-W out

Q: Heat load (KW) W in: Input power (KW) example: 8KW, W out: Output power (KW) example: 3W

Example: Q=W in-W out=8-3=5 (KW)

Time heating method Q=Cp.r.V.ΔT/H

Q: Heat load (KW) Cp: Specific heat at constant pressure (KJ/kg.℃)……4.1868 KJ/kg. ℃,

r: Specific weight (Kg/m3)………1000 Kg/m3 V: Total water volume (m3) Example: 0.5m3

ΔT: water temperature difference (℃)…… ΔT= T2-T1 example: 5℃ H: time (h) example 1h

Example: Q=Cp.r.V.ΔT/H=4.1868*1000*0.5*5/3600=2.908 (KW)

Temperature difference flow method Q=Cp.r.Vs.ΔT

Q: Heat load (KW) Cp: Cp: Specific heat at constant pressure (KJ/kg.℃)……4.1868 KJ/kg. ℃,

r: Specific weight (Kg/m3)…….1000 Kg/m3 Vs: Water flow rate (m3/h) Example: 1.5m3/h

ΔT: water temperature difference (℃)…… ΔT= T2 (outlet water temperature)-T1 (inlet water temperature) Example: 10°C

Example: Q=Cp.r.Vs.ΔT=4.1868 * 1000 * 1.5* 10/3600 = 17.445 (kw)

Common plastic method: Q=W* C*ΔT * S

Q=the required frozen water energy kcal/h W=the weight of plastic raw materials KG/H Example: W=31.3KG/H

C=Specific heat of plastic raw materials Kcal/KG ℃ Example: Polyethylene PE C=0.55 Kcal/KG℃

ΔT= is the temperature difference between the melting temperature and the product film, ℃ generally (200℃)

S = safety factor (take 1.35-2.0) Generally take 2.0

Example: Q= W* C*ΔT * S=31.3 * 0.55 * 200 * 2.0 = 6886 (kcal/h)

When you need a chiller, Here is the Necessary info to quote.

1.What is your cooling capacity?_____    Kcal/hr  or   _____KW or _____RT?
2. What's your power supply? For example: 380V-50Hz-3N (N=Phase )
3.What refrigerant type do you require? R22 or R134a or R407c?
4. What's your ambient temperature?

And what is your chiller inlet and outlet water temperature?
5. Which industry do you use the chiller in?