Monoblock Refrigeration Unit for Cold Storage Refregarating Long Term, Fresh Vegetables And Fruits

Monoblock Refrigeration Unit for Cold Storage Refregarating Long Term, Fresh Vegetables And Fruits

A monoblock refrigeration unit (also called an all-in-one refrigeration unit) is a compact, integrated system that combines key components—compressor, condenser, evaporator, fan, and controls—into a single module. It is widely used in small to medium-sized cold storages, especially ideal for long-term refrigeration of fresh vegetables and fruits, thanks to its simplicity in installation, space-saving design, and reliable performance.

1. What is a Monoblock Refrigeration Unit?

A monoblock unit integrates all critical refrigeration components into one pre-assembled package:

Compressor: The "heart" that circulates refrigerant (e.g., R449A, R513A, or R32—environmentally friendly, low-GWP options).

Condenser: Dissipates heat from the refrigerant (air-cooled, typically with fans, suitable for outdoor or well-ventilated indoor installation).

Evaporator: Absorbs heat from the cold storage interior (air-cooled, with fins and fans to circulate cold air).

Controls: Built-in thermostats, pressure switches, and safety devices to regulate temperature and protect the system.

Its compact design eliminates the need for complex on-site piping between components, making it easy to install and suitable for cold storages with limited space (e.g., 10–500 m³, common for farms, cooperatives, or small distributors).

2. Key Design Considerations for Long-Term Fruit & Vegetable Storage

Fresh vegetables and fruits require precise environmental control for long-term preservation: temperature stability (0–10°C, depending on the produce), high humidity (60–95%) to prevent dehydration, and minimal air turbulence to avoid physical damage. A monoblock unit for this purpose must address these needs:

a. Temperature Control Precision

Target Temperature Range: Most fruits (e.g., apples, pears) and vegetables (e.g., carrots, cabbage) thrive at 0–4°C; tropical fruits (e.g., bananas, mangoes) need 12–15°C. The unit’s thermostat should maintain ±0.5°C stability to prevent spoilage from temperature fluctuations.

Evaporator Design: The evaporator (responsible for cooling air) should have low-temperature differential (ΔT = 5–8°C between refrigerant evaporation and storage air). A smaller ΔT reduces over-cooling and minimizes moisture loss from produce.

Fan Speed Regulation: Variable-speed fans (instead of fixed-speed) adjust airflow based on cooling demand, avoiding excessive cold air direct contact with delicate produce (e.g., leafy greens) that can cause wilting.

b. Humidity Retention

High humidity is critical for fresh produce—low humidity leads to weight loss, shriveling, and quality degradation. Monoblock units must balance cooling with moisture preservation:

Evaporator Coil Design: Use hydrophilic-coated fins on the evaporator to prevent condensation from turning into frost (which would dehumidify the air). Hydrophilic coatings allow water droplets to flow off the fins and return to the storage air as humidity.

Defrost System Optimization: Avoid over-defrosting (common with electric defrost). Use "smart defrost" (triggered by frost thickness sensors, not fixed timers) to minimize heat input during defrosting—excess heat raises air temperature and lowers humidity.

Optional Humidifier Integration: For produce requiring >90% humidity (e.g., strawberries, lettuce), pair the monoblock unit with a low-energy ultrasonic humidifier, controlled by a humidity sensor to maintain set levels.