System pressure adjustment

As long as the heat exchange temperature meets the process requirements, I think reducing the return water valve setting has little impact; on the contrary, it can increase the residence time of the circulating water and thus improve the heat exchange efficiency. To achieve effective energy savings and reduction in consumption for the device

In my opinion, the supply pressure should be taken into account from the outset in the design of a circulating water system; rather than relying solely on closing the return valve to control the water pressure. This approach results in low thermal efficiency of the heat exchange equipment, as well as high investment costs.

Increase the supply pressure of the circulating water; reducing it will affect the heat exchange efficiency

Ultimately, the function of a heat exchanger is to control the heat transfer amount or the outlet temperature. Second is the pressure you mentioned. Is the low water supply pressure ultimately due to an increase in the total water supply volume? Is it still the issue that the water supply pump has insufficient head? This needs to be confirmed! The process technician closes the return water valve here because they believe that the water supply volume is too high; by reducing the water flow slightly, the pressure can be increased. It can’t be said to be a problem, but it’s still the same issue mentioned earlier: by reducing the amount of water flowing through the loop, the heat exchanger may fail to meet the requirements regarding heat transfer capacity or outlet temperature. It is necessary to measure the inlet and outlet temperatures of the circulating water in the heat exchanger to determine the temperature difference If the temperature difference is too small, it’s fine for the process operator to close the return water valve. If the temperature difference is already very large, then the return water valve cannot be closed any further.

As long as the heat exchange performance of the equipment meets the process requirements, it can be reduced in size; after all, the heat exchanger isn’t designed to operate at 100% capacity

1. For a cooler to achieve heat transfer, it is necessary for the hot and cold media to reach a thermal equilibrium. The heat of the circulating water is controlled by three parameters: the inlet and outlet temperatures and flow rates. 2. The flow rate of the circulating water through the tube bundle is determined by the pressure difference between the inlet and outlet, rather than just the inlet pressure. Provided that the pressure difference between inlet and outlet is higher than the system resistance, the greater the pressure difference, the greater the flow rate. 3. In production units, there is an upper limit on the inlet pressure of the circulating water. For upstream valves, closing the outlet valve increases the backpressure on those valves and thus raises the pressure behind them; however, for coolers, this reduces the pressure difference of the circulating water.

Adjust the circulating water valve to increase the supply flow and decrease the return flow, using the return flow to regulate the heat exchanger.

After reading everyone’s replies, I personally believe that a return water valve can be used to regulate pressure only when both the pressure difference and temperature difference in the heat exchange equipment are within appropriate ranges. But then why do so many devices require interlocks for low and very low cooling water pressure alerts?

①Observe whether the cooling temperature of the medium reaches the process parameter; whether the cooling medium pipeline can withstand such operation over the long term after pressure is built up in it; and whether it is due to insufficient pressure for a short period of time or some other reason We considered that the refrigerant pressure was insufficient, so we installed a booster pump on the pipeline

What you just said is the idea that I hear most often being implanted by device manufacturers. For equipment manufacturers, the greater the import pressure, the higher the water flow rate within the equipment, and thus the better the cooling effect. It was actually misguidance caused by the lack of proper technical support from the equipment manufacturer’s sales staff. There are two types of cooling for heat exchange equipment: one is continuous cooling, such as cooling an electric furnace, where water flows continuously inside the furnace. Such a system does not consider pressure, but rather the pressure difference. That is, the difference between the inlet pressure and the outlet pressure of the device is within this range. This pressure difference indicates the pressure loss of the device (sometimes referred to as pipe loss or water resistance); as long as the pressure difference is greater than this value, the device can operate properly! The second type of temperature reduction is intermittent instantaneous cooling, which generally occurs in high-end equipment. That is, there is a solenoid valve in the equipment for import; this valve is controlled by temperature – it opens when the temperature exceeds a certain value, allowing water to flow through rapidly in order to cool the equipment down. When the temperature drops to a certain level, the solenoid valve closes and water flow stops, preventing further cooling. The purpose of this is that when there are 20 such devices in the system, a total of 200 cubic meters of water is needed for cooling, but if only 5 of them are in use, then 50 cubic meters of water will be sufficient! This helps to minimize the system’s total energy consumption. Of course, you can avoid using this solenoid valve to turn intermittent cooling into continuous cooling. It’s this kind of intermittent temperature drop; it also depends on the pressure difference, with the pressure being only slightly higher than that of continuous water supply. So don’t blindly trust the equipment manufacturers; instead, communicate more with those who are knowledgeable in technology, as many salespeople don’t understand it. You asked casually, and he just replied casually as well. Because once a contract is signed, the technology loses all its value! Some people even refer to 40 KPa as 4 kilograms of pressure. I’ve encountered a case like this related to energy savings; when the client heard that a pressure of 4 kilograms was required, they purchased a pump with a 50-meter length of tubing (while the resistance of other tubes was 10 meters). As soon as the pump started operating, it caused overcurrent, so they had to control the pressure at the pump’s inlet at 4 kilograms by closing the valve at the end. Our subsequent energy-saving solution was to switch to 15-meter pumps, which have worked well. The power savings rate exceeds 60%. By switching to another pump, the company saves 200,000 in electricity costs per day. The boss is overjoyed; it’s equivalent to the company earning a net profit of 200,000 per year. If my explanation isn’t clear enough, you can message me privately.