Heat pumps features
A heat pump is a device that transfers heat from one place to another, from a cooler area to a warmer one, so it can both heat and cool indoor spaces depending on seasonal needs. Unlike traditional heating systems which generate heat by burning fuel, heat pumps move existing heat, requiring significantly less energy. This makes them a key technology in the transition to sustainable and low-carbon heating and cooling solutions.
Click here to learn more about how a heat pump works.
Heat pumps are essential devices for heating and cooling buildings by utilising the thermal energy present in the environment. A key component of heat pumps is the compressor, which plays a crucial role in the heat transfer process. There are three main types of compressors used in heat pumps:
- Scroll compressors
- Screw Compressors
- Centrifugal Compressors
Scroll and screw compressors are positive displacement (volumetric) compressors that work by mechanically reducing the volume of a fixed amount of gas to increase its pressure. Centrifugal compressors, on the other hand, are dynamic. They increase the pressure of the gas by imparting kinetic energy into it using rapidly rotating blades or impellers. Scroll compressors are typically used in small to medium sized units, screw compressors in medium to large units and centrifugal compressors in large units. Each compressor has its characteristics that define the best application for each type.
Daikin has extensive experience in developing and manufacturing compressors across a range of technologies, including inverter scroll, screw, and centrifugal types.
Explore our full range of heat pumps here, or contact us for more information.
Explaining Volume Ratio in volumetric compressors
A fundamental feature of volumetric compressors is the volume ratio, also known as the compression ratio. This ratio defines the relationship between the volume of gas at the start of the compression process and the volume of gas at the end. It indicates the extent to which the gas is compressed in terms of its physical volume. For example, in a reciprocating compressor, the volume ratio is determined by the volume of the cylinder at the beginning and end of the compression stroke.
Example of a reciprocating compressor
The Pressure Ratio is the ratio of the discharge pressure to the intake pressure of the compressor.
This ratio tells us how much the pressure of the gas is increased by the compressor.
Under the assumption of an ideal gas, and considering an isentropic (adiabatic and reversible) compression process, the relationship between the pressure ratio and the volume can be expressed as:
Where y = Cp/Cv with Cp and Cv characteristics of fluid type.
The volume ratio is linked to the compressor design, and thus, the pressure ratio generated by the compressor depends on its geometry. In heat pumps, the operating pressures at the evaporator and condenser are influenced by the source conditions (e.g., outdoor air or geothermal source) and the desired hot temperature.
Based on this, there are three possible situations:
- Ideal situation (Volume ratio = Pressure ratio)
- Over-compression (Volume ratio > Pressure ratio)
- Under-compression (Volume ratio < Pressure ratio)
Compression cycle in the three different situations
In the ideal case, the volume ratio of the compressor matches the pressure ratio, and the energy required is exactly what is required by the compression cycle. If the volume ratio generates a pressure ratio higher than what is required, the extra energy used to over-compress the refrigerant is wasted. In the opposite situation, if the refrigerant pressure at discharge is lower than the pressure inside the condenser, the refrigerant goes back into the compressor, which must use additional energy to get the refrigerant out.
If you're interested in exploring the best compressor option for your project, feel free to get in touch with us. We're here to help you find the most suitable solution.
Advantages of Variable Volume Ratio (VVR) on Daikin screw compressors
To maximize compression efficiency under all conditions, the compressor should be capable of adjusting its volume ratio according to the operating conditions. Daikin Single Screw Compressors are equipped with Variable Volume Ratio technology, which allows the compressor to modulate the volume ratio based on the heat pump's operating conditions. This technology includes a moving mechanism that adjusts the volume of the discharge port, delaying or anticipating the end of compression to minimize under or over-compression phenomena.
Daikin Single-Screw Compressor
This mechanism plays a key role in reducing the operating costs of the heat pump while also maximizing its reliability. These benefits are especially critical in demanding applications, such as those in industrial settings.
To learn more, we invite you to explore this white paper:
Compressor adjusting volume ration form minimum to maximum
Advantages of using Inverter technology
Heat pumps and chillers typically operate at part load for most of their runtime, meaning the compressor often functions under off-design conditions. In these scenarios, maintaining high efficiency and reliability is essential. The Inverter, also known as a Variable Frequency Drive (VFD), is an electronic component that adjusts the compressor’s rotational speed (RPM) by varying the frequency of the motor’s power supply. This modulation allows the compressor to adapt its capacity to match the actual cooling or heating demand. As a result, the system can deliver optimal performance across a wide range of operating conditions, ensuring energy-efficient operation and precise capacity control.
Click here to learn more about Daikin Inverter technology.
Compressors for heat pumps in comfort applications
As capacity requirements increase, the choice of compressor technology evolves accordingly. For lower capacities, typically in residential and light commercial applications, Inverter Scroll Compressors are widely used.
For this type of building, Daikin offers a wide range of air source heat pump units, including the Daikin R-32 EWYT-CZ, with a cooling and heating capacity range of 16 to 90 kW.
In addition, the Daikin EWYE-CZ is a high-temperature air-source heat pump that uses R-454C refrigerant, combining energy efficiency with environmental sustainability. It can provide water temperatures from +20°C to +70°C. The range includes eight models from 16 to 70 kW, all with Daikin Inverter Scroll compressors and operating at ambient temperatures from -25°C to 40°C.
On top of air-sourced configurations, Daikin also offers water-sourced modular heat pumps with scroll compressors, bringing several advantages.
Look at this article to know more or contact us for any further information.
When higher water temperatures are required, the Daikin EWWH-J series is an ideal solution. This water-to-water heat pump, reversible on the water side, is valued for its compact footprint and high reliability. It features a semi-hermetic Single Screw Compressor, with heating capacities ranging from 106 to 243 kW. The unit is optimised for use with R-1234ze refrigerant and can deliver heating water up to +75°C, making it suitable for high temperature heating applications.
Compressors for heat pumps in industrial applications
In the industrial sector, reliability is a key factor, especially in industries such as pharmaceuticals, where HVAC systems play a critical role and can account for up to 65% of total energy consumption. These systems are essential not only for maintaining precise temperature and air quality standards to prevent contamination, but also for ensuring a comfortable working environment. Given their significant energy consumption, optimising HVAC performance is critical for both cost efficiency and environmental sustainability. For higher capacity requirements, such as those found in process and industrial applications, systems are typically equipped with Inverter-driven screw compressors. This technology is better suited to large, demanding environments where performance, flexibility and energy efficiency are paramount. In such applications, appropriately sized units, often with inverter screw compressors, are essential to provide the required capacity while maintaining optimum efficiency and reliability.
The use of inverter-driven screw compressors offers many benefits, as demonstrated by the Daikin water-to-water heat pumps from VZ series. In its R-1234ze refrigerant version, the VZ series can provide hot water temperatures up to +90°C, combining high efficiency with low environmental impact. The VZ series covers a wide range of capacities, with heating capacities from 409 to 1924 kW.
Learn more here to find out Daikin supplied 7 VZ heat pumps for a hospital renovation project.
Frequently Asked Questions on Daikin Heat Pumps
Where are Daikin heat pumps manufactured?
Daikin heat pumps are manufactured in Italy, at the headquarters and heart of Daikin Applied Europe, located in Ariccia (Rome). This factory is dedicated to producing high-quality HVAC equipment, including two main types of heat pumps: air-source and water-source.
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How to purchase a Daikin heat pump?
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How to rent a Daikin’s heat pump?
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How to get support for Daikin heat pumps?
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How to buy spare parts for a Daikin heat pump?
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