COP (energy efficiency value) =Q (cooling capacity) /W (refrigerator) +W (external circulation pump) +W (internal circulation pump) +W (cooling water pump) +W (fan). The greater the COP value, the more energy saving.
1. Cold prediction technology based on the lowest energy consumption of refrigeration unit.
According to the formula: Q=C*L*△T(C: specific heat capacity; L: real-time flow: △T: temperature difference between supply and return water)
By increasing the flow meter and temperature, the cooling capacity can be calculated, and the cooling capacity required on site can directly act on the quantity and load change control of the refrigerator to eliminate the lag and synchronize the load change, thus achieving the purpose of energy saving.
2. Optimization technology based on the lowest energy consumption of refrigeration unit.
According to the formula: Q=C*L*△T(C: specific heat capacity; L: real-time flow: △T: temperature difference between supply and return water)
By accurately calculating the cooling capacity, the refrigeration unit is controlled to optimize.
For example, three freezers are running and three freezers are working at 40% load at the same time, so one can be completely closed and the other two can increase the load, which improves the efficiency of freezers and solves the problem that in the existing control technology, each freezer controls loading and unloading according to the temperature difference, resulting in multiple freezers working at the same time in the low efficiency area.
3、? Refrigerator load regulation control technology based on minimum energy consumption
Because the energy efficiency ratio of each refrigerator varies greatly in different load areas, the load of each refrigerator is adjusted by adjusting the outlet water temperature of each refrigerator in the selected unit to achieve the lowest energy consumption. The energy consumption decreases by 3% when the outlet water temperature increases by 65438 0℃. When the temperature drops by 65438 0℃, the energy consumption increases by 2%.
4, based on the lowest energy consumption, the small temperature difference compensation adjustment of the refrigeration host.
Based on the minimum energy consumption, the small temperature difference compensation adjustment of the refrigeration host (within a certain temperature range, determined according to the process data of the enterprise, the assumed range is 0.5℃ of the set temperature).
For example, the chiller adjusts the load according to the temperature difference between the supply water and the return water. For example, when the water supply temperature is 7 degrees and the backwater temperature is 12 degrees, the temperature difference is 5 degrees. At this point, the chiller is fully loaded. If the return water temperature becomes 1 1.9 degrees, the chiller is still at full load, and the chiller is at the critical point of load reduction, the system will automatically increase the set water outlet temperature of the chiller by 0.
5. Minimum energy consumption effluent temperature adjustment control technology based on temperature and humidity changes.
According to the temperature and humidity of the external environment, the outlet temperature of the refrigerator is automatically adjusted to achieve the purpose of energy saving. Install a temperature and humidity sensor, and properly adjust the outlet water temperature through the change of external temperature and humidity (without affecting the field use).
6. Control algorithm of circulating pump group based on minimum energy consumption.
The second core control technology of ZW-8000 energy management control system: the control algorithm and equipment with the lowest energy consumption of circulating pump group based on big data management. This technology has been patented. . The traditional water pump control mode is constant pressure water supply or power frequency water supply, which has limited energy saving efficiency.
(1). Install a pressure transmitter at the most unfavorable end of the outlet header and pipeline of the chilled water circulating pump to measure the lift, and install an electromagnetic flowmeter on the circulating water return header to monitor the return water flow in real time.
(2) Establish a database according to the detected real-time head, flow and the characteristic curve formula of the circulating water pump.
(3) The energy consumption of the circulating pump combination in this state is collected in real time through the electric energy meter installed on each water pump, and a group of combinations with the lowest energy consumption is selected for output.
7, regional cooling balance technology
(1). A throttle valve is set on each branch pipe of the water separator. The control target of the electric regulating valve is the original design temperature difference of 5℃, and a pressure sensor is set at the most unfavorable end of each area to ensure the normal work of each area.
(2) Under the condition of controlling the same temperature difference, when the required cooling capacity in this area decreases with the equipment load or the outside air temperature, the required cooling capacity decreases and the flow entering this area decreases. So as to achieve the purpose of energy saving.
Optimal backwater temperature control technology of cooling water
The temperature of cooling water will affect the cop value of refrigerator. According to the cop characteristics of the refrigerator, the optimal cooling water return temperature is set to control, so that the refrigerator always works in the working state with the highest cop.
8, cooling tower fan number and cascade control
The frequency and number of fans are controlled according to the backwater temperature of cooling water.
9. Control and management of safe operation measures of refrigeration unit
1) —— The interlock safety protection control system controls the start and stop of the equipment in the interlock, so as to avoid potential safety hazards caused by human control.
2)— Low-limit protection of chilled water flow and flow regulation protection. The control system is equipped with low-limit protection of chilled water flow to avoid the surge or icing of evaporator caused by low chilled water flow. At the same time, the adjustment rate of chilled water flow is controlled in the process of chilled water flow adjustment, so as to prevent the copper tube from cracking due to too high refrigerant flow of evaporator caused by too fast adjustment rate.
3)— Flow regulation protection of cooling water system? The lower limit protection of cooling water flow is set in the control system to avoid too low flow.
The condensation pressure is too high, which leads to the decrease of refrigeration capacity and compressor failure.
4)— Low-temperature protection of chilled water outlet and cooling water reflux to prevent freezing phenomenon caused by low temperature of chilled water in evaporator, and provide high-temperature and low-temperature protection for cooling water outlet and inlet of unit to prevent unit from breathing due to high temperature.
Vibration and inefficient operation, at the same time to prevent the cooling water temperature is too low to make the unit unable to work normally.
5)-Use differential pressure protection between chilled water supply and return water? Prevent the scene that the flow rate of chilled water at the most unfavorable point of the empty system is insufficient due to too low pressure difference, and also prevent the explosion of chilled water pipeline caused by extreme load drop or blockage.