Here are the four basic factors that affect chiller sizing and selection:

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1. Desired coolant temperature. This is the coolant temperature at the inlet of your process or equipment. It is important to measure the temperature at this point to allow for coolant heating as it travels from the chiller to the process. The longer the distance to be covered, the higher the potential heat gain. This heat gain can be minimized by insulating the cooling line and positioning the chiller as closely as practical to the equipment or process being cooled.

2. Heat load. This is the amount of heat that needs to be removed. It is usually expressed in BTU/hour or watts. The heat load value is often provided by the equipment manufacturer. If not, it can be calculated using the following formula:

Heat load   = Flow rate x Fluid density x Fluid specific heat x Constant x ∆T°

BTU/hour

Watts

Flow rate

=

Gallons/minute

Liters/minute

Fluid density

=

Pounds/gallon

Grams/liter

Fluid specific heat

=

BTU/pound°F

Joules/gram°C

Constant

=

60

0.

∆T° = the difference between the inlet and outlet temperatures of the equipment being cooled

=

°F

°C

Properties of Common Cooling Fluid

Fluid

Fluid Density

Specific Heat

Lbs/gal

Grams/liter

BTU/lb°F

Joules/gram°C

Water @ 77° (25°C)

8.333

1

4.181

50% water, 50% propylene glycol @ 50°F (10°C)

8.744

.25

0.835

3.493

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50% water, 50% ethylene glycol @ 50°F (10°C)

8.992

.72

0.776

3.245

It is generally recommended that 20 to 50% be added to the calculated heat load to provide a safety factor if the chiller will be operated at ambient temperatures above 68°F (20°C) or at high altitude, or if the heat output of the device is variable. This will also provide a margin of safety for future cooling needs. That said, resist the temptation to build more of a safety margin into your chiller than is necessary; an oversized chiller will not cool your equipment any more effectively but will cost more to purchase and operate.

3. Coolant flow and pressure. These parameters are normally provided by the equipment manufacturer and are a function of the surface area and the heat transfer characteristics of the process/material being cooled. It is crucial that your chiller deliver coolant at the proper flow rate and pressure — if the flow rate or pressure is too high, the equipment being cooled may be damaged; if it is too low, the heat removal will be inadequate. Your chiller supplier can help you specify the type and size of coolant pump most suitable for your needs.

4.   Condenser heat dissipation. The final factor influencing chiller/heat exchanger selection is how the heat removed will be dissipated. Devices with air-cooled condensers exhaust heat into the surrounding air and require only power and ventilation for operation. Devices with water-cooled condensers transfer heat to the facility’s cooling water supply. Chillers with remote condensers (i.e., the condenser is located outside the facility) are also available. These are quieter, require less space, and do not add heat to the building interior, thus reducing summer cooling costs. However, they are more expensive to install and are not easily relocated.

Naturally, there are other factors — such as heating capability, remote temperature tracking, DI water capability, etc. — that affect how a chiller is ultimately configured. Conscientious chiller vendors will take all these into consideration when helping you select the best chiller for your particular application.

Be prepared to provide the following information when contacting your chiller supplier:

• Desired coolant temperature at the inlet to your equipment or process
• Anticipated heat load, as calculated or specified by the equipment manufacturer
• Cooling fluid flow rate and pressure requirements
• Internal heat dissipation, space, and portability needs
• Special requirements, such as remote temperature tracking or DI piping

Energy-Efficient Chiller Guide

Commercial chillers are designed to cool large areas in various applications. Energy-efficient chillers use advanced technology to minimize the amount of electricity they need to operate, helping reduce energy costs and their impact on the environment. As a business owner or engineer, you want to reduce your operational costs and greenhouse gas emissions. However, you may be worried about selecting a commercial chiller that may not adequately meet the cooling demands of your facility or one that may end up being inefficient in the long run.

Most efficient refrigeration systems have expanded in new directions in most industries, including medical, food processing and manufacturing. Our energy-efficient chiller guide will help you choose the most suitable chiller for your needs. You will learn what makes them efficient and which factors to consider. This information can help you confidently choose the right commercial chiller system that will balance upfront costs with long-term savings.

Tips for Maximizing Chiller Efficiency

Heating, ventilating and air conditioning (HVAC) systems, including chillers, consume more than 40% of a building’s energy. Replacing old models with efficient chillers can give you a competitive advantage by reducing production costs and utility bills.

To keep a commercial chiller sustainable in the long run, use the following tips to maximize its efficiency.

• Conduct regular maintenance: Schedule routine maintenance checks. Check refrigerant levels, clean necessary parts, and ensure proper airflow to keep the chiller operating at its peak.
• Maintain refrigerant levels: A chiller’s efficiency is closely related to how well its compressor pumps the refrigerant through the system. Leaks are often the cause of low refrigerant levels, so make sure to monitor any changes.
• Optimize set points: Adjust set points for chilled water temperature and system pressures to balance temperature needs with energy efficiency.
• Use free cooling: Where possible, use ambient air or water sources instead of running chillers continuously.
• Implement variable speed drives (VSDs): Upgrade your chiller to a model with variable speed compressors and pumps to match cooling load variations more accurately.
• Run multiple parallel devices: With more than one unit, equipment can run more efficiently, even when they run at half capacity. Instead of spreading multiple systems to run at full capacity, placing more chiller systems in parallel may benefit from optimizing the heat transfer surface area while reducing pressure drops.

How to Calculate Chiller Efficiency

Generally, you can use one of two formulas to calculate chiller efficiency. The first measure of the cooling efficiency of a chiller is the coefficient of performance (COP). The second chiller efficiency calculation uses the energy efficiency ratio (EER). The higher the COP or EER number, the better the chiller efficiency per unit of electricity consumed.

COP vs. EER

While COP and EER are both good metrics, they differ in how they are calculated and what they represent:

• COP: A chiller’s coefficient of performance is the ratio of the cooling output to the energy input of a chiller at a specific operating condition. It indicates how efficiently the chiller converts energy into cooling. To calculate chiller efficiency using COP, divide the cooling capacity by the electrical power input. Both the cooling output and energy input are measured in watts (W) or kilowatts (kW).
• EER: The energy efficiency ratio uses a standardized set of operating conditions. It measures the ratio of the cooling output to the energy input, giving a snapshot of the chiller’s efficiency at a particular point. To measure chiller efficiency using EER, divide the cooling capacity in British thermal units (Btu) by the electrical power input in W or kW.

Let’s say a chiller produces 5,000 kW of cooling while consuming 500 kW of electricity. Its COP would be:

• 5,000 kW / 500 kW = 10

In this case, the chiller produces 10 kW of cooling for every 1 kW of consumed electricity.

Finding the chiller efficiency as EER follows the same calculation. You can convert the chiller’s Btu to kW by multiplying it by 0. before using the COP formula. For example, if a chiller’s cooling capacity is 150 Btu, you’ll calculate its chiller efficiency as follows:

• 150 Btu x 0. = 0. kW cooling capacity
• 0. kW / 500 kW = 21.975

A 150 Btu chiller produces almost 22 kW of cooling for every 1 kW of consumed electricity.

Chiller Approach Temperature

A third way to measure efficiency is to check the approach temperature of a chiller. Approach temperature is the difference between the temperature of chilled water leaving the chiller and the temperature of the refrigerant inside the chiller. It indicates how effectively a chiller is transferring heat and cooling the water. The formula for chiller approach temperature is:

• Condensing refrigerant temperature – water supply temperature

A low approach temperature indicates that a chiller is working at a high efficiency. In contrast, a high approach temperature is a common sign of an inefficient chiller. The higher the approach temperature, the harder the compressor needs to work in the cooling process, using more energy.

Features to Look For

Optimizing often starts with the basic components of any equipment. Consider the following features when searching for or customizing an energy-efficient chiller for your organization:

• Evaporators: Larger evaporators can absorb more heat from industrial processes or the surrounding air to cool it down.
• Compressors: To minimize energy consumption, features such as multiple refrigerant circuits, screw compressor slider valves and digital scroll compressors can help with efficient refrigerant compression.
• Condensers: Water regulation and three-way valves can reduce energy consumption and lower the head pressure of condensers.
• Expansion valves: To regulate the flow of refrigerant into the evaporator more efficiently, opt for electronic expansion valves to maintain a consistent cooling process.
• Fan motors: Energy-efficient fan features include electronically commutated fan motors that enhance electric performance and stable temperatures.
• Hot liquid tank: Using a hot water heat recovery feature can help cool the liquid refrigerant flow while providing extra cooling for the compressor.
• Fluid cooler: A fluid cooler can boost the system’s overall EER. It allows a chiller to use ambient air to cool, requiring less energy.

Factors to Consider When Evaluating Chillers

You’ll want to consider a few factors when buying an industrial chiller. When it comes to energy efficiency, in particular, you must look at additional needs, especially when you work in specialized industries. Consider these factors when evaluating different chillers:

• Cooling requirements: Determine the specific temperature range and cooling capacity you need, the type of equipment that needs cooling and future expansions.
• Type of chiller: You may want to decide between air-cooled and water-cooled chillers. Air-cooled chillers are suited for applications with limited water availability whereas water-cooled chillers are more efficient but require a water source.
• Seasonal energy efficiency ratio (SEER): Similar to EER, SEER takes into account the cooling output over an entire cooling season divided by the total electrical energy input during the same period. This comprehensive view of the system measures the efficiency of a chiller over time.
• Smart controls: Choose chillers with advanced control systems that optimize performance based on real-time conditions.
• Variable speed technology: Chillers with variable speed compressors and pumps can reduce energy consumption by adjusting their cooling capacity, depending on demand.
• Long-term savings: Compare all models’ initial costs, operating costs and potential long-term savings. Investing in an efficient chiller will result in more cost savings in the long run.
• Maintenance-friendly design: See which chillers have easy access to components for maintenance and cleaning tasks.
• Integration with existing systems: Ask yourself whether a specific chiller will best integrate with your current infrastructure, ensuring its controls and automation system are compatible.

Operation and Maintenance Best Practices

Energy-efficient commercial chillers need regular maintenance and servicing like any other equipment to keep them running optimally. Operating them without regular checks can lead to significant challenges, including higher energy consumption rates, inadequate cooling and system breakdown. Fortunately, you can take specific measures to improve a chiller’s operation:

• Maintain daily operating logs to detect common problems and predict potential chiller system maintenance needs.
• Clean condenser coils every few months to minimize corrosion and ensure heat transfers from the refrigeration cycle.
• Measure the glycol concentration levels to avoid blockages and ruptured tubes.
• Monitor refrigerant levels and top up when needed to keep chilling operations going.
• Inspect the motor and starting mechanisms regularly.
• Check for leaks, damaged pipelines and faulty connections.
• Prevent air and moisture from flowing into the chiller system.
• Clean chiller tubing regularly.
• Provide staff with training and awareness on best chiller operation and maintenance practices to maximize the longevity of chiller systems.
• Upgrade chiller controls to digital systems to provide real-time monitoring and performance so you can respond to inefficiencies quickly.
• Use temperature setbacks to lower energy consumption in off-peak periods.
• Implement a preventive maintenance program.

Examples of Energy-Efficient Chillers

The type of chiller you need for your facility depends on your products, the size of your facility and your output. While most new models are designed to work more efficiently, the following examples will give you the best energy output results.

• Water-cooled chillers: Water transfers heat better than air, which makes water-cooled chillers more efficient and consistent in their operation. They also tend to last longer than air-cooled chillers.
• Scroll chillers: These chillers use a scroll compressor to raise the refrigerant’s temperature and pressure. Since they contain fewer moving parts, they produce less noise and operate smoothly. New scroll chiller models have a built-in variable frequency drive (VFD) and a higher cooling output per energy unit than other chiller systems.
• Low-temperature chillers: Some applications require keeping fluid temperatures low, such as petrochemical processes and ice rinks. Low-temperature chillers use special heat transfer fluid to ensure the equipment produces fluid that remains below a specific temperature.
• Screw chillers: A screw compressor transports the coolant through this chiller system. Screw chillers are ideal for high-rise buildings since they operate quietly and have low maintenance costs.
• HVAC chillers: These chillers cool water or other fluids to provide air conditioning or process cooling in various industrial and commercial applications. The energy efficiency of an HVAC chiller depends on its size and type.
• Plastic processing chillers: In the plastics industry, chillers need to maintain temperature control. Whether you choose an air-cooled or water-cooled chiller, the right plastic processing chiller system can enhance your product quality while reducing energy costs.

Frequently Asked Questions

We listed some common queries about efficient chillers and energy efficiency formulas if you’re looking for short answers to frequently asked questions.

How Do You Calculate the Energy Efficiency of a Chiller?

You can calculate the energy efficiency of a chiller by using the COP or EER formula. Both measure the cooling output’s ratio to a chiller’s energy input. However, COP indicates how effectively the chiller converts energy into cooling, while EER gives a snapshot of the chiller’s efficiency at one point. The energy efficiency of COP and EER have similar calculations, but because EER is measured in Btu, you need to convert the input to kW before it can be calculated.

Another way to ensure a chiller is still working efficiently is to measure its approach temperature, which is the difference between the condensing refrigerant and water supply temperatures. A low approach temperature indicates the chiller is working well, while a high COP or EER number indicates a highly energy-efficient chiller.

How Many kW per Ton for Chiller Efficiency?

The best chiller efficiency range depends on the type of chiller, its weight, the operating conditions and whether it is partially or fully loaded. Lower kW/ton values represent higher efficiency. Air-cooled chillers’ efficiency can range between 0.8 kW/ton and 1.2 kW/ton, and water-cooled chillers from about 0.45 kW/ton to 0.64 kW/ton.

There’s room for improvement in efficiency the moment air-cooled chillers reach above 1.2 kW/ton and water-cooled chillers above 0.64 kW/ton.

Which Type of Chiller Is the Most Efficient?

Generally, water-cooled chillers are more energy-efficient than air-cooled chillers. They tend to be more compact, have longer operating lives and produce less noise. However, every industry and type of facility has different needs, and the most efficient chiller for one may be inadequate for another application. When choosing the best one for your work output, consider a chiller’s life cycle and operating costs.

Some chillers have components that help compress refrigerants with fewer moving parts and built-in VFDs for a higher cooling output per energy unit. Other types tend to last longer or operate on systems that keep temperatures consistent in industries where temperature plays a major role. It’s best to speak to a professional to determine which type would be the most efficient for your facility.

Invest in Energy-Efficient Chillers From Smart Family of Cooling Products

When selecting commercial chillers, it’s important to prioritize energy efficiency. Smart Family of Cooling Products specializes in manufacturing different types of chillers, including air-cooled, water-cooled and low-temperature chillers. We also build industrial custom refrigeration products with your specifications and processes in mind. Our unique expertise allows us to provide experienced consultation if you need help choosing the most energy-efficient and cost-effective chillers.

For more info on our chillers, contact our team online, and we’ll get back to you as soon as possible.

For more China High-Efficiency Water-Cooled Screw Chillerinformation, please contact us. We will provide professional answers.