How Many Types of Refrigeration Compressors Are There?

When selecting refrigeration equipment, do you often face this dilemma: for the same project, some recommend reciprocating compressors for their reliability, others suggest scroll compressors for their quiet operation, and still others insist that screw compressors are the only choice for continuous heavy-duty operation — who is right? Choosing the wrong type leads to soaring energy consumption and excessive noise at best, or frequent compressor burnout and costly project rework at worst.

Why are there so many types?​ Because refrigeration scenarios vary drastically — the load difference between a freezer and a cold room can be dozens of times; the operating conditions of a convenience store AC and a shopping mall central AC are completely different; household refrigerators and chemical plant refrigeration are worlds apart. No single compressor can handle all scenarios. The essence of selection is not finding the "best," but finding the "most suitable."

The real "selection difficulty" often arises in intermediate scenarios — projects with long piping and numerous bends where oil return is a concern: do you choose a model with an oil separator, or compensate through piping design? The cooling capacity is moderate, but the system runs at part load most of the year — do you choose a variable-frequency screw or two fixed-frequency scrolls in rotation? This is not a question of "whether the cooling capacity is sufficient," but rather "which technical route is more reliable given your site conditions."

This article provides a comprehensive overview of the five mainstream types of refrigeration compressors on the market, explaining the core characteristics, applicable boundaries, and selection logic of each type, so that you have a clear basis and path to follow for your next selection.

Product Positioning

From the perspective of compression principle, refrigeration compressors are divided into two major categories: positive displacement​ and dynamic (centrifugal). Structurally, they derive into five mainstream types:

A rule of thumb for selection: sorted by cooling capacity — small capacity goes to rotary, medium to scroll, medium-to-large to screw, extra-large to centrifugal, and special conditions to reciprocating.

I. Reciprocating (Piston) Compressors

Working Principle:​ The crankshaft-connecting rod mechanism drives the piston to reciprocate within the cylinder, completing the processes of suction, compression, and discharge.

Core Characteristics:

• Most mature technology with the richest production experience; relatively low cost

• Wide exhaust pressure range, up to 320 MPa (industrial applications)

• High thermal efficiency; adiabatic efficiency of medium-to-large units reaches 0.7–0.85

• A single compressor can adapt to different gases; strong operating condition adaptability

• Disadvantages:​ Complex and bulky structure; many wearing parts; high maintenance workload; vibration during operation; discontinuous discharge; can only be used for fixed-frequency (50/60 Hz), not suitable for inverter applications

Application Scope:

• Cold rooms and freezing/refrigeration markets (mainly semi-hermetic reciprocating)

• Refrigerators, small freezing and refrigeration equipment

• Single-unit cooling capacity typically ranges from 5.8 to 1745 kW

Selection Advice:

• Small cooling capacity (<5 HP):​ Hermetic reciprocating remains the mainstream choice for refrigerators and small freezers

• Medium cooling capacity (15–40 HP low-temp scenarios):​ Semi-hermetic reciprocating still has its place, especially at evaporation temperatures below -25°C, where reciprocating compressors are more reliable than scroll due to the natural advantage of multi-stage compression

• Suitable for fixed-frequency, intermittent operation​ scenarios

• Do NOT select for inverter scenarios​ — reciprocating cannot adapt to frequency variation

• If low noise, low vibration, and long life are priorities, consider scroll or screw compressors first

II. Rotary (Rolling Rotor) Compressors

Working Principle:​ An eccentric rotor rotates inside the cylinder, working with a vane to form compression chambers, completing gas intake, compression, and discharge.

Core Characteristics:

• Extremely simple structure with few parts — the most compact of the five compressor types

• Small size and light weight; 40%–50% smaller in volume than reciprocating types

• Smooth operation, low noise, minimal vibration

• No suction valve design​ — longer suction time, small clearance volume

• Excellent inverter compatibility, smooth startup

• Disadvantages:​ Very low single-unit cooling capacity ceiling (single rotor ≤3 HP); limited pressure ratio, not suitable for low-temp high-pressure conditions; slight vane wear over long-term operation

Application Scope:

• Residential AC, refrigerators, and other small refrigeration equipment

• Cooling capacity typically between 1000–7000 W, used in AC units ≤3 HP

• Twin-rotor compressors can be used in 4–6 HP AC units (some up to 8 HP)

• Light commercial refrigeration equipment such as dehumidifiers

Selection Advice:

• Residential AC ≤3 HP, refrigerators:​ Rotary is the most cost-effective choice

• Small equipment sensitive to cost and size:​ Rotary's compact structure and low cost are ideal

• Inverter scenarios:​ Rotary has excellent inverter compatibility with fast startup response

• Do NOT select for large cooling capacity, low-temp, or high-pressure-ratio scenarios​ — the single-unit capacity ceiling is a hard limitation

III. Scroll Compressors

Working Principle:​ Composed of a pair of intermeshing fixed and orbiting scrolls. The fixed scroll is stationary while the orbiting scroll rotates around an eccentric axis. The crescent-shaped sealed chambers formed between the scrolls continuously contract from the outside toward the center, completing gas compression.

Core Characteristics:

• Extremely low operating noise and virtually no vibration​ — the quietest among the five compressor types

• No reciprocating parts (no pistons, connecting rods, etc.); high reliability and long life

• Volumetric efficiency up to 98%

• Top-tier variable frequency performance; part-load efficiency far exceeds

• Disadvantages:​ Core scroll machining requires extremely high precision (micron-level), resulting in high manufacturing cost; limited single-unit cooling capacity range (typically ≤30 HP); performance degrades under high pressure ratios; moderate liquid slugging resistance

Application Scope:

• Mid-to-high-end residential and commercial AC, heat pumps

• Mainstream choice for AC units above 6 HP

• Freezing, refrigeration, cold rooms (3–30 HP)

• Low-noise scenarios: hospitals, laboratories, data centers, etc.

• Excellent energy efficiency in常规 low-temp range (0°C to -40°C)

Selection Advice:

• Venues with strict noise requirements​ (hospitals, hotels, residences): Scroll is the first choice

• Inverter scenarios:​ Scroll's inverter performance is top-tier, with significant part-load efficiency advantage

• Small-to-medium cooling capacity (3–30 HP), pursuing high efficiency and quiet operation:​ Scroll is the optimal solution

• Do NOT select for extra-large cooling capacity scenarios​ — single-unit capacity range is limited

• Liquid return protection must be implemented; liquid slugging resistance is moderate — it is recommended to install a suction accumulator in the suction line

• Two-stage scroll for low temp is a rising star in recent years:​ For cold room scenarios with evaporation temperatures below -25°C, two-stage scroll can operate stably with 15%–20% higher energy efficiency than single-stage reciprocating, rapidly replacing part of the semi-hermetic reciprocating market share

IV. Screw Compressors

Working Principle:​ A pair of intermeshing helical male and female rotors rotate, drawing gas into the rotor grooves. As the rotors turn, the gas is gradually compressed and finally discharged through the exhaust port.

Core Characteristics:

• High reliability:​ Few parts, no wearing components; overhaul interval can reach 40,000–80,000 hours

• Positive displacement gas delivery:​ Volumetric flow is almost unaffected by discharge pressure, maintaining high efficiency over a wide range

• Supports 10%–100% stepless capacity modulation

• Insensitive to wet operation (strong liquid slugging resistance)

• Disadvantages:​ Relatively high noise (requires soundproof machine room); high rotor machining precision; complex oil separation system required; part-load efficiency lower than centrifugal

Application Scope:

• Medium-to-large commercial scenarios (40–150 HP)

• Large central AC, industrial refrigeration

• Commercial freezing/refrigeration, food and pharmaceutical industries

• Process refrigeration in chemical, food processing, etc.

Selection Advice:

• Medium to large cooling capacity (40–150 HP):​ Screw is the main choice

• Scenarios requiring stepless capacity modulation:​ Screw's 10%–100% slide valve modulation offers clear advantages

• Scenarios with frequent part-load operation:​ Note that screw efficiency at part load is not linear — slide valve modulation maintains high efficiency in the 60%–100% load range, but efficiency drops significantly below 40%. If the project runs at 30%–50% load year-round, evaluate variable-frequency screw or two fixed-frequency scroll rotation方案

• Noise-sensitive scenarios:​ Require soundproof machine room

• Evaporation temperature below -20°C:​ Single-stage screw economy deteriorates; consider economizer or two-stage solutions

V. Centrifugal Compressors

Working Principle:​ Low-pressure gas enters the center of the impeller from the side, gaining kinetic and pressure energy from the centrifugal force generated by high-speed impeller rotation. The kinetic energy is then converted to pressure energy through a diffuser.

Core Characteristics:

• Largest single-unit cooling capacity​ — the representative of dynamic compressors

• Small size, minimal footprint; weight is 5–8 times lighter than reciprocating at the same capacity

• No wearing parts such as valves or piston rings

• Large gas volume, high efficiency

• Disadvantages:​ Only suitable for extra-large cooling capacity; completely unsuitable for small flow, high pressure-ratio scenarios (risk of "surge"); narrow stable operating range; extremely high manufacturing precision and cost

Application Scope:

• Extra-large commercial and industrial refrigeration (150 HP–300 HP and above)

• Large building central AC, district cooling

• Industrial centralized cooling

• Cooling capacity above 580 kW gives centrifugal a cost advantage

Selection Advice:

• Cooling capacity >580 kW (approx. 165 HP):​ Centrifugal offers relatively lower cost and higher reliability

• Extra-large cooling capacity, continuous full-load operation:​ Centrifugal is the only choice

• Do NOT select for small-to-medium cooling capacity or scenarios with frequent varying conditions​ — centrifugal has a narrow stable operating range and surge risk

• Average service life approx. 80,000 hours, but installation workload is heavy and lubrication system is complex

• Magnetic bearing centrifugal is a recent trend:​ Eliminates mechanical friction, extremely high part-load efficiency, significantly reduced maintenance cost — suitable for projects with the highest demands for energy efficiency and reliability

Comprehensive Selection Comparison Table

Summary: Three Questions for Selection

Returning to the opening question — the difficulty of selection essentially stems from too much information and vague criteria. When facing a selection, ask three questions:

Question 1: What cooling capacity is needed?​ — Capacity is the starting point of all selection. ≤3 HP → rotary; 3–30 HP → scroll; 40–150 HP → screw; >165 HP → centrifugal; special low-temp conditions → consider reciprocating.

Question 2: Under what operating conditions will it run year-round?​ — More full-load or part-load? Evaporation temperature at -5°C or -30°C? Frequent on/off cycles? These questions determine whether to choose scroll or screw, fixed-frequency or inverter.

Question 3: What are the site constraints?​ — Noise requirements (hospitals/hotels → prioritize scroll)? Sufficient power supply capacity (screw/centrifugal have high starting current)? Dedicated machine room available (screw is noisy, needs soundproofing)? Long piping (oil return issue needs early evaluation)?

Once these three questions are answered, the selection direction is set. The rest is simply matching and confirming technical parameters. Choosing the right compressor makes your project half successful.

We carry these products and know them inside out —

LG QK/QJ/QP Series:​ The king of small-capacity rotary compressors — the cost-effective first choice for residential AC, refrigerators, and light commercial equipment.

Tecumseh TAG/FH/CAJ/TAJ Series:​ Classic hermetic reciprocating compressors — the backbone of cold rooms, display cases, and commercial refrigeration.

Secop SC Series:​ Complete CL/FT coverage — a reliable partner for light commercial and professional refrigeration.

Hitachi DH/DHM/AA/DC/DHD Series:​ The benchmark of scroll technology — fewer parts, less vibration, lower noise; fixed crankshaft + direct suction design enhances volumetric efficiency.

GMCC HSM/PA/PH Series:​ From residential AC to data centers, heat pumps to freezing/refrigeration — solid technology, high cost-effectiveness, the strength choice for large-scale projects.

Danfoss SM/HRP/HCJ/SZ/MTM/MTZ Series:​ SM/SZ scroll compatible with R410A/R407C/R22, the mainstay for commercial AC and heat pumps; HRP/HCJ high-efficiency scroll; MTM/MTZ hermetic reciprocating for medium/high-temp applications.

Whether you are a refrigeration contractor, equipment OEM, as long as you have refrigeration needs, please feel free to contact us. We look forward to cooperating with you!