stefano filippini - lu-ve spa - nuovo aero-refrigerante per il miglioramento della qualita’ della...

XV EUROPEAN CONFERENCE MILANO 7th-8th JUNE 2013 CSG

Latest Technology in Refrigeration and Air Conditioning Under the Auspices of the PRESIDENCY OF THE COUNCIL OF MINISTERS

FRESH FRUIT CONSERVATION:EXPERIMENTAL RESULTS FROM A NEW AIR COOLER CAPABLE OF IMPROVING THE QUALITY OF THE FOOD PRODUCTS AND REDUCING ENERGY CONSUMPTION

Stefano Filippini, Umberto Merlo (LU-VE Group)Giovanni Lozza (Politecnico di Milano)



• Refrigeration is the technique which allows mankind to store

food products and easily retrieve them in times and places that are different to the ones in which they were harvested and processed.



1. REQUIREMENTS OF THE FRUIT DURING CONSERVATION

2. BASIC CRITERIA OF THE NEW “VALUE DEFENDER” AIR COOLER

3. KEY STUDY – LARGE APPLE COLD STORE

4. CONCLUSIONS

SUMMARY



Respiration. Transpiration. Production of Ethylene. Ripening.

POST-HARVEST “KEY” PROCESSES

REQUIREMENTS OF THE FRUIT DURING CONSERVATION



RESPIRATION…why limit it?

WITH LOW

RESPIRATION

COLD REDUCES RESPIRATION

IDEAL: COLD CHAIN FROM FIELD TO SHOP

INCREASE- LIFE- FRESHNESS

DECREASE

- WEIGHT LOSS- HEAT EMITTED- ENERGY

CONSUMED

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VEGETABLE PRODUCTS AND RESPIRATORY INTENSITY

PRODUCT Respiratory activitymgCO2 kg-1 h-1

Seeds Dried Fruits, Dates

< 5

Apples, Citrus Fruits, Kiwi, Grapes Potatoes, Onions, Garlic

5 - 10

Apricots, Bananas, Cherries, Peaches, nectarines, Pears, Plums

Carrots, Cabbage, Lettuce, Peppers, Tomatoes

10 - 20

Strawberries, Mixed Berries, Avocado Cauliflower, Lima Beans

20 - 40

Artichoke, Green Beans, Spring Onions, Brussels Sprouts

Cut Flowers

40 - 60

Asparagus, Broccoli, Peas, Spinach, Mushrooms, Sweetcorn

> 60



TRANSPIRATIONLoss of water

vapour emitted from the surfaces of the product exposed to the air, through the cuticle, stomata, etc.

Internal factors

Fruit and vegetable species.

Type of tissue.

Integrity and hygiene conditions.

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TRANSPIRATION

Loss of watervapour emitted from the surfaces of the product exposed

to the air, through the cuticle, stomata, etc.

External factors

Relative Humidity (<RH; >transpiration)

Temperature (> temperature > transpiration)

Movement of air (increase in transpiration rate)

Physical barriers (to avoid air-product contact)




2. BASIC CRITERIA OF THE NEW ”VALUE DEFENDER” AIR COOLER


4. CONCLUSIONS

SUMMARY



The air cooler - is the most important unit

of the cooling system

BASIC SELECTION CRITERIA

Based on the application

- connects the product and the refrigeration system

- determines the quality of the stored products



NEW AIR COOLER RANGE

• Special design for lowest energy consumption

• Fan on pressure side• Angular design for higher

loading in cold store and best air circulation

• EC fans • Refrigeration circuit

optimized to operate with very small ΔT (brine)



PRODUCT CONSTRUCTION. Fan on suction or pressure side ?

Construction on pressure side allows the reduction of air dehumidification, a crucial parameter for the proper conservation of fresh fruits and vegetables



IMPORTANCE OF HUMIDITY AND ΔT1The exchange area:

bears on the quantity of cooling capacity that can be transferred towards the product

determines the quality of “cold” produced for the ΔT

determines the degree of RH, more important than temperature for correct conservation






4. CONCLUSIONS

SUMMARY



KEY STUDY – LARGE APPLE COLD STORE

To verify the efficiency of the new VALUE DEFENDER, a comparison test was carried out with a traditional CUBIC unit

ProductGolden Delicious Apples (620,000 kg/2,053 bins)

• Controlled atmosphere

• Time (days): approx. 180

• Cold room size (m): 23.3 x 12.9 x 8 (h.)

• Equal external surfaces (m2): 596

• Room temperature (C°): 0.9 – 1.4;

• Room humidity: 93 – 95%

• Ventilation min. 7 hours/day

• Geometry (mm) 55x55; tube ø12.7mm

Cubic Room 31

Value DefenderRoom 30



KEY STUDY – LARGE APPLE COLD STORE

Both cold rooms were specifically equipped with:

4 anemometers Precision scales to continuously measure weight loss in a

row of bins 18 measuring points (for each cold room) of the temperature

at the core of the apples Measurement of the glycol temperature Measurement of humidity and temperature in the cold room Measurement of the values of O2, CO2, ethylene in the air Differential gauge to measure pressure drop between each

heat exchanger Measurement of the electrical power draw of the fans



COOLER - COLD ROOM INTERACTION

CFD simulations predicted the velocity field and temperature within the cold room; the degree of reliability of the predicted values verified by measurement.



RESULTS: APPLE CORE TEMPERATURE

The new VALUE DEFENDER enabled stable operating temperature to be reached in 8 days against 11 with a standard solution.



RESULTS: ROOM HUMIDITY

0

10

20

30

40

50

60

70

80

90

100

0 5 10 15 20 25 30

Rela

tive

hum

idity

%

Days

Fan on suction side

Blower fans

Relative humidity in the cold rooms was identical, but with the new VALUE DEFENDER humidification was reduced by 11%



AIR DISTRIBUTION CFD SIMULATION

The CFD simulation shows a much more even air distribution with new VALUE DEFENDER air cooler, simulation well confirmed by anemometer installed inside the cold rooms

NEW VALUE DEFENDER TRADITIONAL AIR COOLER



RESULTS: ENERGY CONSUMPTION AND WEIGHT LOSS

Advantages of new VALUE DEFENDER:

Energy consumption -19% (-34% during initial cool down period)

Weight loss reduction 1.51% (vs. 1.79%),

i.e. -18.5% (+1700kg apples) Same product quality after conservation More uniform air temperature in cold room with

blow through unit



RESULTS: WEIGHT LOSS

Room No. Months %Gross %Gross/monthRoom 30 (Value Defender) 6.33 1,34 0,212 (best)Room 31 6.00 1.60 0.267Other 1 7.00 1.87 0.27Other 2 7.20 1.76 0.24Other 3 6.00 1.74 0.29Other 4 6.00 2.06 0.34Other 5 7.00 1.73 0.25Other 6 6.10 1.92 0.31Other 7 6.50 1.53 0.24Other 8 7.00 2.06 0.29Other 9 7.20 1.58 0.22Other 10 6.00 1.43 0.24Other 11 5.80 1.30 0.22Average existing rooms 0.264






4. CONCLUSIONS

SUMMARY



CONCLUSIONS

The new VALUE DEFENDER has been developed by studying the requirements of the product to be stored

Energy consumption reduced by 19%

High quality fruit conservation

Weight loss reduced by 18%



Our thanks to Consorzio MELINDA – Ing. L. Fadanelli LONGOFRIGOR – Mr. Longo



BASIC SELECTION CRITERIA

Based on the application

Storage of fresh products

Storage of packaged products

Storage of frozen products

Storage/rapid temperature reduction (chilling)

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