closed-loop conditioning In a closed-loop system with systems, water circulates in the system in a closed loop. In this cycle, the evaporation of the system water, its contact with the air and the effects that change the other biological or chemical properties of the water can be ignored. In closed-loop systems, heat is transferred from the hot process to the cooling water, then in another heat exchanger the heat is discharged from the cooling water to the environment. In closed-loop systems, heat is usually removed by air-cooling in an open-loop system or fin-fan coolers.
What are the Closed Circuit Conditioning System Features:
There are many applications where a wide variety of closed systems are used, from heating buildings to cooling in primary metal production. Descriptive examples of when a closed system is used instead of an open system are given below;
- It is an important process where a malfunction that may occur in the cooling water system can create very important problems.
- An extremely hot process in which scale formation on heat transfer surfaces must be stopped.
- When a cooler with a temperature below ambient or 32 ᵒF (0ᵒC) is required
- When water temperature above boiling temperature is required (eg pressurized hot water systems)
- When a higher level of control is required
closed-loop conditioning Closed cooling systems required can be used in freezing processes operating below freezing or for cooling systems with high heat flux such as steel casting moulds. Closed cooling systems may have the following specific features;
- These systems often consist of different metals galvanically bonded to each other. These metals are mild steel and copper alloys and infrequently aluminum, stainless steel and other metals.
- These systems are designed for minimal make-up water and blowdown, but often a large loss of water.
- Since there is no blowdown in the design of these systems, filtration of the returned water is recommended.
- System volume can be as little as 10 gal (0.04m3) or as large as 7 million gallons (26.500m3).
- Some systems operate with no water flow, intermittent stops.
What are the Problems in Loop Systems with Closed Circuit Conditioning:
- Microbial Growth
Corrosioncan generally be controlled with minimal metal loss, as high doses of inhibitors can be loaded. Likewise, scale formation can be minimized by using softened make-up water. However, water losses due to leakage or microbial degradation of the used can cause an increase in corrosion and scale formation.
Institutionally, under the conditions of a fully closed-loop system, barren Although all of the constituent components (such as calcium carbonate, calcium sulfate, magnesium salts and silica) accumulate on metal surfaces, it does not create a noticeable result because of very small amounts. However, in a typical system, water leakage requires make-up water and the scale-forming ions contained in the make-up water are added to the ions in the closed system water. Each time water is added to the system, continuous precipitation occurs and a significant amount of scale can form, causing blockage of water passageways and even reduced heat transfer.
In a medium-sized closed system, the system receives little sunlight, is low in oxygen, and contains very little nutrients. microbial growthmay not be considered a problem. But in reality, microbial growth can be very important and create huge problems. Leaks in the system require more make-up water, the added water carries more oxygen, debris, nutrients into the system and inoculates new microbial organisms. Leakages in the process provide high amounts of nutrients for microorganisms. Most closed systems have tanks that are open to the atmosphere or have airflow closures so that oxygen levels can be at or near saturation. Finally, some microbial organisms can use some corrosion inhibitors such as nitrite as nutrients. All these factors show how microbial problems occur in closed cooling water systems. Microbial problems contribute to contamination, corrosion and reduced heat transfer. In fact, biofilms are among the most insulating deposits to be encountered on heat transfer surfaces.