Podcast
Questions and Answers
EASY What type of systems are associated with chilled water-cooling systems and hot water heating systems?
EASY What type of systems are associated with chilled water-cooling systems and hot water heating systems?
- Open loop systems
- Closed loop systems (correct)
- Semi-closed systems
- Semi-open systems
What is the purpose of a chiller in a closed loop system?
What is the purpose of a chiller in a closed loop system?
- To purify the water
- To heat the water
- To circulate the water
- To cool the water (correct)
What type of fluids are used in closed loop systems?
What type of fluids are used in closed loop systems?
- Refrigerant only
- Water, glycol solutions, or salt brines (correct)
- Steam only
- Oil only
Why is corrosion less likely to occur in chillers compared to boilers or condensers?
Why is corrosion less likely to occur in chillers compared to boilers or condensers?
What is the primary cause of corrosion in chillers?
What is the primary cause of corrosion in chillers?
What is a characteristic of closed loop systems?
What is a characteristic of closed loop systems?
What is a common issue in closed loop cooling and heating systems?
What is a common issue in closed loop cooling and heating systems?
What type of corrosion occurs when dissimilar metals are in physical contact with each other and exposed to a fluid?
What type of corrosion occurs when dissimilar metals are in physical contact with each other and exposed to a fluid?
Which of the following can accelerate corrosion in heat exchangers?
Which of the following can accelerate corrosion in heat exchangers?
What is the purpose of adding chemicals to the cooling system?
What is the purpose of adding chemicals to the cooling system?
What type of corrosion occurs when one particular metal is preferentially attacked?
What type of corrosion occurs when one particular metal is preferentially attacked?
What is the benefit of sodium nitrite in cooling systems?
What is the benefit of sodium nitrite in cooling systems?
What is the purpose of installing heat exchangers in a specific way?
What is the purpose of installing heat exchangers in a specific way?
What happens when fluid flow is too low in heat exchangers?
What happens when fluid flow is too low in heat exchangers?
What is the purpose of periodic cleaning of heat exchangers?
What is the purpose of periodic cleaning of heat exchangers?
What type of corrosion inhibitor is molybdate?
What type of corrosion inhibitor is molybdate?
What is the estimated material cost of re-tubing a chiller?
What is the estimated material cost of re-tubing a chiller?
What happens when a metal gives off ions in a galvanic cell?
What happens when a metal gives off ions in a galvanic cell?
What is the approximate cost to replace a chiller with a capacity of 850 tonnes?
What is the approximate cost to replace a chiller with a capacity of 850 tonnes?
What is a common problem in heat exchangers, especially if there is fluid leaking into the system?
What is a common problem in heat exchangers, especially if there is fluid leaking into the system?
What is the purpose of a bypass line with a filter in a closed cooling system?
What is the purpose of a bypass line with a filter in a closed cooling system?
What is the maximum percentage of make-up water that should be added to a closed loop system per day?
What is the maximum percentage of make-up water that should be added to a closed loop system per day?
What is the result of water freezing in a closed cooling system?
What is the result of water freezing in a closed cooling system?
What is the purpose of freeze stats in chillers?
What is the purpose of freeze stats in chillers?
What type of solution is used to prevent freeze-up in HVAC cooling coils?
What type of solution is used to prevent freeze-up in HVAC cooling coils?
What is the risk in hot water closed-loop systems?
What is the risk in hot water closed-loop systems?
What is the risk of freezing in hot water heating systems?
What is the risk of freezing in hot water heating systems?
What is the purpose of using glycol and water solutions in heating systems?
What is the purpose of using glycol and water solutions in heating systems?
MEDIUM What happens to the metal that gives off ions in a galvanic cell?
MEDIUM What happens to the metal that gives off ions in a galvanic cell?
Why is it important to keep heat exchangers free of deposits?
Why is it important to keep heat exchangers free of deposits?
What is the effect of high fluid flows in heat exchangers?
What is the effect of high fluid flows in heat exchangers?
What is the purpose of adding sodium nitrite to cooling systems?
What is the purpose of adding sodium nitrite to cooling systems?
What type of corrosion occurs when one particular metal is preferentially attacked?
What type of corrosion occurs when one particular metal is preferentially attacked?
What is the benefit of using molybdate corrosion inhibitors in mixed metallurgy systems?
What is the benefit of using molybdate corrosion inhibitors in mixed metallurgy systems?
Why is it important to install heat exchangers in a specific way?
Why is it important to install heat exchangers in a specific way?
What happens when fluid flow is too low in heat exchangers?
What happens when fluid flow is too low in heat exchangers?
What is the purpose of periodic cleaning of heat exchangers?
What is the purpose of periodic cleaning of heat exchangers?
What is the effect of excessively high or low fluid flows on corrosion?
What is the effect of excessively high or low fluid flows on corrosion?
What is the primary benefit of using a closed loop system in cooling and heating applications?
What is the primary benefit of using a closed loop system in cooling and heating applications?
Which of the following is NOT a common issue in closed loop cooling and heating systems?
Which of the following is NOT a common issue in closed loop cooling and heating systems?
What is the primary cause of corrosion in chillers?
What is the primary cause of corrosion in chillers?
What is the purpose of a pump in a closed loop chilled water system?
What is the purpose of a pump in a closed loop chilled water system?
What type of fluid is commonly used in closed loop heating systems?
What type of fluid is commonly used in closed loop heating systems?
What happens to the chilled water in a closed loop system after it absorbs heat from the process fluid?
What happens to the chilled water in a closed loop system after it absorbs heat from the process fluid?
What is the purpose of the light blue lines in Figure 1?
What is the purpose of the light blue lines in Figure 1?
What is a common issue in both closed loop cooling and heating systems?
What is a common issue in both closed loop cooling and heating systems?
What is the primary method to prevent solids fouling in heat exchangers?
What is the primary method to prevent solids fouling in heat exchangers?
What is the approximate cost of replacing a chiller with a capacity of 1750 tonnes?
What is the approximate cost of replacing a chiller with a capacity of 1750 tonnes?
What is the consequence of biological fouling in heat exchangers?
What is the consequence of biological fouling in heat exchangers?
What is the purpose of adding dispersants in cooling systems?
What is the purpose of adding dispersants in cooling systems?
What is the risk of freezing in cooling systems that operate at higher temperatures?
What is the risk of freezing in cooling systems that operate at higher temperatures?
What is the purpose of using glycol and water solutions in HVAC cooling coils?
What is the purpose of using glycol and water solutions in HVAC cooling coils?
What is the effect of water freezing in a closed cooling system?
What is the effect of water freezing in a closed cooling system?
What is the purpose of freeze stats in chillers?
What is the purpose of freeze stats in chillers?
What is the risk in hot water closed-loop systems?
What is the risk in hot water closed-loop systems?
What is the maximum percentage of make-up water that should be added to a closed loop system per day?
What is the maximum percentage of make-up water that should be added to a closed loop system per day?
HARD Why is galvanic corrosion more likely to occur in chillers?
HARD Why is galvanic corrosion more likely to occur in chillers?
What is the primary benefit of using a closed loop system in cooling and heating applications?
What is the primary benefit of using a closed loop system in cooling and heating applications?
What is the consequence of solids fouling in heat exchangers?
What is the consequence of solids fouling in heat exchangers?
Why is corrosion less likely to occur in chillers compared to boilers or condensers?
Why is corrosion less likely to occur in chillers compared to boilers or condensers?
What is the primary method to prevent scaling in heat exchangers?
What is the primary method to prevent scaling in heat exchangers?
What is the primary cause of biological fouling in heat exchangers?
What is the primary cause of biological fouling in heat exchangers?
What is the purpose of the pump in a closed loop chilled water system?
What is the purpose of the pump in a closed loop chilled water system?
What is the consequence of high fluid flows in heat exchangers?
What is the consequence of high fluid flows in heat exchangers?
What is the primary mechanism by which sodium nitrite protects ferrous metals from corrosion?
What is the primary mechanism by which sodium nitrite protects ferrous metals from corrosion?
What is the primary reason why molybdate is a more effective corrosion inhibitor than sodium nitrite in mixed metallurgy systems?
What is the primary reason why molybdate is a more effective corrosion inhibitor than sodium nitrite in mixed metallurgy systems?
What is the primary consequence of selective leaching in cooling systems?
What is the primary consequence of selective leaching in cooling systems?
What is the primary reason why it is important to install heat exchangers in a specific way?
What is the primary reason why it is important to install heat exchangers in a specific way?
What is the primary effect of high fluid flows on heat exchangers?
What is the primary effect of high fluid flows on heat exchangers?
What is the primary benefit of using a closed loop system in cooling and heating applications?
What is the primary benefit of using a closed loop system in cooling and heating applications?
What is the primary reason why scaling is a lesser concern in closed cooling systems compared to open cooling systems?
What is the primary reason why scaling is a lesser concern in closed cooling systems compared to open cooling systems?
What is the primary reason why it is important to periodically check and adjust nitrite concentrations?
What is the primary reason why it is important to periodically check and adjust nitrite concentrations?
What is the primary consequence of biological growth within cooling systems?
What is the primary consequence of biological growth within cooling systems?
What is the purpose of using a brine solution of water and calcium chloride or glycol in refrigeration systems that use closed cooling loops?
What is the purpose of using a brine solution of water and calcium chloride or glycol in refrigeration systems that use closed cooling loops?
What is the primary reason why molybdate is more effective at protecting brass than sodium nitrite?
What is the primary reason why molybdate is more effective at protecting brass than sodium nitrite?
What is the estimated cost of re-tubing a chiller with a capacity of 2650 tonnes?
What is the estimated cost of re-tubing a chiller with a capacity of 2650 tonnes?
What is the primary consequence of galvanic corrosion in heat exchangers?
What is the primary consequence of galvanic corrosion in heat exchangers?
What is the primary method to prevent solids fouling in heat exchangers?
What is the primary method to prevent solids fouling in heat exchangers?
What is the consequence of not treating the make-up water in cooling systems that operate at higher temperatures?
What is the consequence of not treating the make-up water in cooling systems that operate at higher temperatures?
What is the primary benefit of using a closed loop system in cooling and heating applications?
What is the primary benefit of using a closed loop system in cooling and heating applications?
What is the purpose of adding biocides in cooling systems?
What is the purpose of adding biocides in cooling systems?
What is the risk associated with hot water closed-loop systems?
What is the risk associated with hot water closed-loop systems?
What is the purpose of using glycol and water solutions in heating systems?
What is the purpose of using glycol and water solutions in heating systems?
What is the consequence of not using demineralized, distilled, or reverse osmosis water in cooling systems that operate at higher temperatures?
What is the consequence of not using demineralized, distilled, or reverse osmosis water in cooling systems that operate at higher temperatures?
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Study Notes
Closed Loop Systems
- Closed loop systems are associated with chilled water-cooling systems, hot water heating systems, and internal combustion engine cooling systems.
- These systems recirculate the working heat transfer fluid and use minimal amounts of make-up water.
- The heat exchange fluids may be treated water, glycol solutions, or salt brines.
Chillers
- Chillers are heat exchangers that cool fluids.
- The process fluid (chilled water or brine) is continuously circulated in a closed loop.
- The chiller may use refrigerant or some other cold process fluid to chill the water.
Water Quality Issues
- Closed loop cooling and heating systems both suffer from water quality issues, including:
- Corrosion
- Solids fouling
- Scaling
- Biological fouling
Corrosion
- Corrosion can occur due to galvanic action, especially when dissimilar metals are in contact with each other and exposed to a fluid.
- Corrosion can also occur wherever deposits form, making it important to keep heat exchangers free of deposits.
- Corrosion inhibitors, such as sodium nitrite and molybdate, can be used to eliminate corrosion.
- Sodium nitrite is an anodic corrosion inhibitor that forms a protective iron oxide surface film, but it is not effective for copper or copper alloys.
- Molybdate inhibitors provide the best corrosion protection for systems of mixed metallurgy.
Fouling
- Solids fouling can occur due to fluid leaking into the system, corrosion, scaling, and biological growth.
- Strainers or filters can be used to avoid fouling, and should be cleaned or replaced about once a year.
- Bypass lines with filters can also be used to maintain a low level of suspended impurities.
Scaling
- Scaling can be an issue in closed cooling systems, especially at higher temperatures.
- Make-up water should be demineralized, distilled, or reverse osmosis to prevent scaling.
- Make-up water should never exceed 0.1% of the system capacity per day, or 2% of the system capacity per month.
Biological Fouling
- Biological fouling can occur if leaks occur, and can decrease heat transfer efficiency and promote corrosion.
- Biocides and dispersants can be used to remove biofilms and prevent biological fouling.
Freezing
- Water can freeze if the refrigerated medium is below 0°C, which can cause damage to pipes, tubes, and equipment.
- Chillers are equipped with freeze stats to prevent freezing damage.
- Glycol solutions can be used to prevent freeze-up in HVAC cooling coils and refrigeration systems.
Heating Systems
- Hot water closed-loop systems are similar to those used for chilled water, but operate at higher temperatures, which can magnify the risks of scale formation, deposition, fouling, and corrosion.
- The treatment and monitoring of these conditions is similar to those used for closed cooling systems.
- Hot water heating systems may also be susceptible to freezing, especially in vestibule heaters and air handling unit-heating coils.
Closed Loop Systems
- Closed loop systems are associated with chilled water-cooling systems, hot water heating systems, and internal combustion engine cooling systems.
- These systems recirculate the working heat transfer fluid and use minimal amounts of make-up water.
- The heat exchange fluids may be treated water, glycol solutions, or salt brines.
Chillers
- Chillers are heat exchangers that cool fluids.
- The process fluid (chilled water or brine) is continuously circulated in a closed loop.
- The chiller may use refrigerant or some other cold process fluid to chill the water.
Water Quality Issues
- Closed loop cooling and heating systems both suffer from water quality issues, including:
- Corrosion
- Solids fouling
- Scaling
- Biological fouling
Corrosion
- Corrosion can occur due to galvanic action, especially when dissimilar metals are in contact with each other and exposed to a fluid.
- Corrosion can also occur wherever deposits form, making it important to keep heat exchangers free of deposits.
- Corrosion inhibitors, such as sodium nitrite and molybdate, can be used to eliminate corrosion.
- Sodium nitrite is an anodic corrosion inhibitor that forms a protective iron oxide surface film, but it is not effective for copper or copper alloys.
- Molybdate inhibitors provide the best corrosion protection for systems of mixed metallurgy.
Fouling
- Solids fouling can occur due to fluid leaking into the system, corrosion, scaling, and biological growth.
- Strainers or filters can be used to avoid fouling, and should be cleaned or replaced about once a year.
- Bypass lines with filters can also be used to maintain a low level of suspended impurities.
Scaling
- Scaling can be an issue in closed cooling systems, especially at higher temperatures.
- Make-up water should be demineralized, distilled, or reverse osmosis to prevent scaling.
- Make-up water should never exceed 0.1% of the system capacity per day, or 2% of the system capacity per month.
Biological Fouling
- Biological fouling can occur if leaks occur, and can decrease heat transfer efficiency and promote corrosion.
- Biocides and dispersants can be used to remove biofilms and prevent biological fouling.
Freezing
- Water can freeze if the refrigerated medium is below 0°C, which can cause damage to pipes, tubes, and equipment.
- Chillers are equipped with freeze stats to prevent freezing damage.
- Glycol solutions can be used to prevent freeze-up in HVAC cooling coils and refrigeration systems.
Heating Systems
- Hot water closed-loop systems are similar to those used for chilled water, but operate at higher temperatures, which can magnify the risks of scale formation, deposition, fouling, and corrosion.
- The treatment and monitoring of these conditions is similar to those used for closed cooling systems.
- Hot water heating systems may also be susceptible to freezing, especially in vestibule heaters and air handling unit-heating coils.
Closed Loop Systems
- Closed loop systems are associated with chilled water-cooling systems, hot water heating systems, and internal combustion engine cooling systems.
- These systems recirculate the working heat transfer fluid and use minimal amounts of make-up water.
- The heat exchange fluids may be treated water, glycol solutions, or salt brines.
Chillers
- Chillers are heat exchangers that cool fluids.
- The process fluid (chilled water or brine) is continuously circulated in a closed loop.
- The chiller may use refrigerant or some other cold process fluid to chill the water.
Water Quality Issues
- Closed loop cooling and heating systems both suffer from water quality issues, including:
- Corrosion
- Solids fouling
- Scaling
- Biological fouling
Corrosion
- Corrosion can occur due to galvanic action, especially when dissimilar metals are in contact with each other and exposed to a fluid.
- Corrosion can also occur wherever deposits form, making it important to keep heat exchangers free of deposits.
- Corrosion inhibitors, such as sodium nitrite and molybdate, can be used to eliminate corrosion.
- Sodium nitrite is an anodic corrosion inhibitor that forms a protective iron oxide surface film, but it is not effective for copper or copper alloys.
- Molybdate inhibitors provide the best corrosion protection for systems of mixed metallurgy.
Fouling
- Solids fouling can occur due to fluid leaking into the system, corrosion, scaling, and biological growth.
- Strainers or filters can be used to avoid fouling, and should be cleaned or replaced about once a year.
- Bypass lines with filters can also be used to maintain a low level of suspended impurities.
Scaling
- Scaling can be an issue in closed cooling systems, especially at higher temperatures.
- Make-up water should be demineralized, distilled, or reverse osmosis to prevent scaling.
- Make-up water should never exceed 0.1% of the system capacity per day, or 2% of the system capacity per month.
Biological Fouling
- Biological fouling can occur if leaks occur, and can decrease heat transfer efficiency and promote corrosion.
- Biocides and dispersants can be used to remove biofilms and prevent biological fouling.
Freezing
- Water can freeze if the refrigerated medium is below 0°C, which can cause damage to pipes, tubes, and equipment.
- Chillers are equipped with freeze stats to prevent freezing damage.
- Glycol solutions can be used to prevent freeze-up in HVAC cooling coils and refrigeration systems.
Heating Systems
- Hot water closed-loop systems are similar to those used for chilled water, but operate at higher temperatures, which can magnify the risks of scale formation, deposition, fouling, and corrosion.
- The treatment and monitoring of these conditions is similar to those used for closed cooling systems.
- Hot water heating systems may also be susceptible to freezing, especially in vestibule heaters and air handling unit-heating coils.
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