What is the cooling system of the computer room refrigeration facility, adsorption refrigeration, and assembly cold storage

What is the cooling system of the computer room refrigeration facility, adsorption refrigeration, and assembly cold storage

Many people have little understanding of the cooling system of the computer room refrigeration facility, adsorption refrigeration, and prefabricated cold storage. The equipment and configuration of the facility cooling system will be different. Due to time and expense reasons, people will be forced to focus disproportionately. In simply designing a system that can only deliver the required capacity, ignoring other factors, however, we should still pay more attention to balance various factors. The following is the cooling system of the above-mentioned computer room refrigeration facilities, adsorption refrigeration, The prefabricated cold storage is further dissected.

　　What is the cooling system of the computer room refrigeration facility?

The design of the cooling system of the data center computer room should have the characteristics of reducing or avoiding system outages related to the installation of new equipment. These characteristics should be applicable to the cooling system in the centralized station building and the cold water pipeline structure in the building. Some of the features include For future equipment, such as water-cooled racks, centralized air conditioners, computer room air conditioners and centralized station equipment, pipeline valves and pipe covers need to be reserved during installation. Centralized stations should consider adding chillers when the load increases , Water pumps and cooling towers.

In order to accept computers and cooling systems in the future, reasonable load management systems and development plans or strategies should be formulated and used. Comprehensive flexibility is often limited by the pipeline distribution system in the centralized station. When the data center is online, avoid From the perspective of operational interruption and implementation costs, it is generally forbidden to increase the capacity by changing the pipe size.

In the control center, there should be various emergency procedures, agreements, personnel lists, etc., which should be updated when they are changed. The power supply of facilities and equipment, such as uninterruptible power supplies (UPS), chillers, units and power feeders, should be monitored , To determine the load increase and available capacity. In addition, a configuration management team or management committee including information technology (IT, and various departments in the facility) should be formed, which can control and manage the infrastructure of the data center.

　　(1) Flexibility

　　 The design of the data center cooling system should be characterized by reducing or avoiding system outages related to the installation of new equipment. These characteristics should be applied to the cooling system in the centralized station building and the cold water pipeline structure in the building. Some of these features include future equipment such as water-cooled racks, centralized air conditioners, computer room air conditioners, and centralized station buildings. Pipe valves and pipe covers shall be reserved for equipment installation. Centralized station buildings should consider adding chillers, water pumps and cooling towers when the load increases.

　　 In order to accept computers and cooling systems in the future, a reasonable load management system should be formulated and used, and development plans or strategies should be developed. Full flexibility is often limited by the pipeline distribution system in the centralized station building. When the data center is online, it is generally prohibited to increase the capacity by changing the pipe size from the perspective of avoiding operational interruption and implementation costs.

　　(2) Scalability

　　The center has sufficient consideration for the expected increase and expansion, otherwise it will be eliminated in a short period of time. The update of computer technology is 2 to 5 years, so the cooling system needs to have the ability to expand to adapt to the increase in load. The design of the piping system (CWS—cooling water system, CHWS—cold water system) in the building should be able to support the cooling load density in the building. Although initial investment often dominates pump selection and pump specifications, pump energy consumption, system flexibility and cold water storage must also be considered to determine the owner's total investment.

　　The centralized computer room should have enough space for future chillers, water pumps and cooling towers. The size of the cold water and cooling water system in the centralized computer room, the size of the water collector, from the first day of operation to the increase in capacity, and the planned capacity in the future, should all be well adapted to its changes, according to full expansion and future The piping selected for the increase in the amount of energy can save energy, and smaller effective components can also be used early in the life of the building. If the budget does not allow for additional costs for future expansion, the owner must ensure that there is available real estate next to the existing centralized computer room.

　　What is adsorption refrigeration?

Adsorption refrigeration is also driven by thermal energy, that is, the use of dual or multiple working fluid pairs to achieve a refrigeration cycle. This is the same as vapor absorption refrigeration. However, it is similar to absorption refrigeration that uses liquid absorbent to absorb and release refrigerant vapor. Different, adsorption refrigeration uses solid adsorbent to adsorb and analyze refrigerant gas. Its working principle is: using the characteristic that the adsorbent has different adsorption capacity at different adsorption temperatures, periodically cooling and heating the adsorbent, so that it alternately produces adsorption and desorption processes. During desorption, the refrigerant gas is released and condensed into a liquid. During adsorption, the refrigerant liquid evaporates to produce refrigeration.

　　(1) Continuous adsorption refrigeration system

　　The adsorption refrigerator composed of two (or more) adsorption beds only needs to alternately complete the adsorption and desorption processes, and can achieve continuous refrigeration.

Suppose that the adsorption bed A is heated and the adsorption bed B is cooled. When the A bed is fully desorbed and the B bed is saturated with adsorption, then the adsorption bed A is cooled and the adsorption bed B is heated. The two alternate operations form a complete continuous refrigeration cycle. . At the same time, during the switching of the two processes, the exhaust heat of the hot bed just after desorption can also be used to heat another cooling bed just after the adsorption, so as to make full use of the heat energy and improve the efficiency of the refrigeration cycle, thus forming a continuous regenerative type cycle.

　　(2) Features of adsorption refrigeration

　　 Compared with vapor compression refrigeration, adsorption refrigeration can save a lot of electricity, reduce the peak load of the air-conditioning seasonal power grid, and can be driven by various thermal energy. In addition to the use of heat generated by boiler steam and fuel gas, low-grade heat sources such as solar energy and various waste heat, exhaust gas, and wastewater can also be used.

　　Simple structure, few operating parts, safe and reliable, using water, ammonia, methanol, etc. as refrigerants, harmless to the environment and atmospheric ozone layer.

Although adsorption refrigeration has great application prospects, some of its shortcomings have greatly reduced its market competitiveness, mainly in: the adsorption and desorption process is relatively slow, the refrigeration cycle period is longer; and the vapor compression and absorption Compared with the type refrigerator, the cooling capacity is relatively small; the thermal coefficient is generally 0.5 to 0.6.

　　(3) Intermittent adsorption refrigeration system

　　 Intermittent adsorption refrigeration uses solar energy to drive the refrigerant, which is mainly composed of an adsorption bed, condenser and evaporator to form a closed system. During the day, the adsorbent bed at ambient temperature is heated by solar energy. After the temperature of the adsorbent rises, the analysis begins, and the refrigerant is desorbed from it. The vapor pressure of the refrigerant in the system gradually rises. When it reaches the saturation pressure corresponding to the ambient temperature, The refrigerant vapor condenses in the condenser and releases latent heat at the same time, and the condensed liquid enters the evaporator for storage. At night, the adsorbent bed is cooled and the adsorption capacity of the adsorbent is increased, so the refrigerant vapor in the evaporator starts to adsorb, resulting in a decrease in gas pressure in the system. At this time, the refrigerant in the evaporator evaporates continuously at low temperature, and the absorption is The heat of cooling the substance achieves the purpose of refrigeration. If other heat sources are used, as long as the adsorbent bed is heated and cooled intermittently, so that the adsorbent can periodically produce desorption and adsorption, it can also achieve the purpose of refrigeration.

　　From the above, we can see that adsorption refrigeration is also liquid vaporization refrigeration. Similar to the vapor compression refrigerator, the adsorption bed utilizes a change in temperature to cause a large change in the adsorption capacity, which leads to a large change in the pressure in the closed system, thereby acting as a compressor. However, the above-mentioned adsorption system is intermittently refrigerating, and the adsorber is in the process of adsorption to produce a cooling effect. After the adsorption is completed, there must be a desorption process to restore the adsorbent state, and then the refrigeration will be stopped.

　　(4) Adsorption refrigerant pair

　　The choice of adsorbent refrigerant working fluid pair is one of the important factors affecting the performance of adsorption refrigerator. The ideal working fluid pair is an adsorbent that requires strong adsorption performance, fast adsorption speed, and good heat transfer effect within the working range, and a refrigerant with a large latent heat of vaporization and a boiling point that meets the requirements. At present, the research on the adsorption working fluid pair is continuously deepening. And development. The more mature ones are zeolite-water, silica gel-water, activated carbon-methanol, metal hydride-oxygen, chloride salts-ammonia and so on. G? Cacciola and G? Restuccia obtained the mature working fluid pair suitable for different temperature zones. Since water has a relatively large latent heat of vaporization and is easy to freeze below 0°C, zeolite-water and silica gel-water are more suitable for air conditioning systems with evaporation temperatures above 0°C. The adsorption capacity of activated carbon for methanol is relatively large, and the adsorption capacity is more sensitive to temperature changes. The latent heat of vaporization of methanol is large, the freezing point is low, the boiling point is higher than room temperature, and it is not corrosive to metal materials such as copper and steel. Therefore, the activated carbon is suitable for solar energy or other low temperatures for methanol. General refrigeration system driven by heat source. However, since methanol is easily decomposed at about 150°C, its working temperature should be lower than 150°C.

　　What is a prefabricated cold storage?

　　Assembled cold storage, also known as assembled cold storage, combined cold storage and movable cold storage, has the characteristics of light weight, compact structure, and good thermal insulation performance. The library body board is prefabricated by the factory, and the refrigeration equipment can be purchased in complete sets and installed on site. The library construction period is short, and it is extremely convenient to disassemble, relocate and rebuild. The library body board is made of prefabricated inner and outer aluminum alloy (also galvanized steel or stainless steel), sandwiched with a sandwich board formed by high-pressure foamed rigid polyurethane or polystyrene with low thermal conductivity. The board surface has Flat or corrugated type. A certain number of pin-off fastening devices or male-male interface devices are used to connect the storage boards. The storage door adopts electric heating to prevent freezing, which is flexible and convenient to open. There is a cage between the bottom of the storage and the indoor floor. Or bottom support empty shelf.

The prefabricated cold storage is equipped with a variety of complete sets of compressors (with water-cooled or air-cooled condensers), thermal expansion valves, air coolers and electric control boxes, a complete set of lighting in the library, etc. The built-in temperature controller can automatically control the shutdown Turn on the compressor and air cooler, and the air cooler is equipped with electric heating wire to automatically defrost, etc., which is easy to operate and the storage temperature is stable. The cooling load is calculated as follows:

　　(1) Refrigeration compressor load

　　 For indoor prefabricated cold storage, due to frequent purchases and shipments, the purchase temperature is relatively high, resulting in large changes in the cooling load. In the load calculation, there is no need to reduce or modify the heat, and set the cold loss compensation coefficient of refrigeration equipment and pipelines to 1.1. Therefore, the load of the refrigeration compressor can be calculated: QJ=1.1(1/εQ1+PQ2+Q4+Q5).

　　(2) Warehouse cooling equipment load

The calculation principle of the cooling equipment load of the fabricated cold storage is basically the same as that of the civil cold storage, but some of the items should be modified according to the characteristics of the fabricated cold storage, where Q1, Q2, Q3, Q4, and Q5 are the heat transfer load of the maintenance structure, Cargo heat, ventilation heat, cold room motor running heat, operating heat, W, 1/ξ is the calculation coefficient of the plate gap, taking 1.1, β is the cargo heat flow coefficient, for the cooling room, freezing room and cargo without cooling Directly enter the cold storage room of the cold storage room. β=1.3, for other cooling rooms (including frozen storage rooms, ice storage rooms and partial cold storage rooms) β=1 pair and indoor assembled cold storage, the food is short-term storage, ventilation and heat can be omitted:

Indoor cold storage does not need to consider solar radiation. Q1 can be calculated as Q1=KF (32℃=tn). For outdoor assembled cold storage, Q1Q is calculated: Q1=KFa(tw=tn), where a is the temperature difference correction coefficient, For the outer side of the enclosure structure, add a ventilated air layer, the outer wall a=1.3, and the roof a=1.6. For the outer side without a ventilated air layer, the outer wall a=1.53 and the roof a=1.87.