|
Key points for selecting screw chillers (water-cooled screw chillers, air-cooled screw chillers):
1 The main control parameters of screw chillers are refrigeration performance coefficient, rated cooling capacity, input power, and refrigerant type.
2 The selection of chiller units should be considered based on the cooling load and purpose. For refrigeration systems that operate under low load conditions for a long time, it is advisable to use multi head piston compressor units or screw compressor units for easy adjustment and energy saving.
3 When selecting chiller units, priority should be given to units with higher performance coefficient values. According to data statistics, the operating time of a general chiller unit at 100% load throughout the year accounts for less than 1/4 of the total operating time. The proportion of operating time at 100%, 75%, 50%, and 25% load within the total operating time is approximately 2.3%, 41.5%, 46.1%, and 10.1%. Therefore, when selecting chillers, priority should be given to models with relatively flat efficiency curves. At the same time, the adjustment range of the load of the chiller unit should be considered when designing and selecting. The multi head screw chiller unit has excellent partial load performance and can be selected according to the actual situation.
4 When selecting a chiller unit, attention should be paid to the nominal operating conditions. The actual cooling capacity of the chiller unit is related to the following factors:
a) Cold water outlet temperature and flow rate;
b) The inlet temperature, flow rate, and fouling coefficient of the cooling water.
5 When selecting a chiller unit, attention should be paid to the normal operating range of the unit, mainly the current limit of the main motor is the current value of the shaft power under nominal operating conditions.
6 In design selection, attention should be paid to: under nominal operating flow conditions, the outlet temperature of cold water should not exceed 15 ℃, and the outdoor dry bulb temperature of air-cooled units should not exceed 43 ℃. If it is necessary to exceed the above range, it should be understood whether the usage range of the compressor is allowed and whether the power of the main motor is sufficient.
Edit this paragraph on the maintenance of screw chillers
Maintenance of screw chiller
1、 After the installation of the screw chiller is completed or it has been out of use for a long time, the cooling rate should be reasonable: it is advisable to control it at 8-10 ℃ per day and maintain it at 0 ℃ for a period of time.
2、 During the maintenance of the screw chiller hangar plate, attention should be paid to the collision and scratching of hard objects on the garage body during use. Because it can cause dents and rust in the storage board, and in severe cases, it can reduce the local insulation performance of the storage body.
3、 Maintenance of the sealing parts of screw chillers. As prefabricated screw chillers are made up of several insulation boards, there are certain gaps between the boards. During construction, these gaps will be sealed with sealant to prevent air and moisture from entering. So, timely repair of some sealing failure areas during use.
4、 Floor maintenance of screw chillers: Generally, insulation boards are used for the floor of small assembled screw chillers. When using screw chillers, it is necessary to prevent a large amount of ice and water from accumulating on the floor. If there is ice, hard objects should not be used to hit and damage the floor during cleaning.
Maintenance of screw chiller
1、 Mold removal, sterilization, and disinfection of screw chillers
The cooking ingredients and foods refrigerated by screw chillers contain certain amounts of fat, protein, and starch. The presence of these nutrients can promote the proliferation and growth of mold and bacteria.
To ensure the quality of refrigeration and cooking ingredients, it is necessary to regularly carry out refrigeration and disinfection work in order to do a good job in refrigeration and hygiene management.
For the sterilization and disinfection of screw chillers, acid disinfectants can be used first. The bactericidal effect of acid disinfectants mainly involves coagulation of proteins in bacterial cells. Common disinfectants include lactic acid, peroxylactic acid, bleach, formalin, etc.
2、 Methods for eliminating odors in screw chillers
1. Reasons for the generation of odors in screw chillers
The so-called odor refers to the abnormal odor produced by the cooking ingredients and food in the screw chiller through physical and chemical changes under the influence of external factors. Over time, this odor adheres to the walls, ceilings, equipment, and tools of the screw chiller. There are generally several reasons for the odor generated in screw chillers, including the presence of an odor before food is consumed.
Before entering the screw chiller, there is a phenomenon of food spoilage, such as spoiled eggs, meat, fish, etc.
The screw chiller that has stored fish, without cleaning, stores meat, eggs, fruits, vegetables and other foods, causing odor infection and spoilage.
The ventilation of the screw chiller is poor, and the temperature and humidity are too high, which leads to the proliferation of mold and the production of mold odor.
The leakage of the refrigeration pipeline of the screw chiller causes the refrigerant (ammonia) to corrode into the food, resulting in the production of odors.
The temperature in the screw chiller does not decrease, causing the meat to spoil and produce a putrid odor. This situation often occurs when fresh meat is not frozen or frozen completely before being transferred to storage.
|
