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Content

Content
Introduction

Ripening room application
Main advantages
Differences with similar ripening systems
Naming convention: rooftop/Chiquita v. curtain/Del Monte
Pallet format and preparation
Room loading
What more to turn the key

Supply repeated for each room

Room electrical board
Computerised control system
Door
Depression system
Ethylene injection system
Air renewal system
Room heating system
Room refrigerating system—direct expansion option
Room refrigerating system—water and glycol option
Consumption comparison among direct expansion and water option
Branched refrigeration circuit
Humidification
Option for a dedicated compressor for each room

Supply common to all the rooms

PC software for ripening and monitor
Central refrigeration unit
Remote condenser and connecting circuit
Electrical board of central unit
Refrigeration main circuit
Oil and refrigerant charge
Ethylene main circuit

Prefabricated panels

Ripening room arrangement
Prefabricated panel specification
Prefabricated panel accessories

Options

Introduction

Ripening room application

ripening and storage of banana boxes, on pallets, for a wide range of formats
ripening with closed or perforated bags, and for every kind of box
standard range from 6 to 48 pallets, on one level or two levels
different ripening rooms on request
partial ripening load from 2 pallets till the maximum capacity
ripening time from three to six days, and ripening stage from two to six

Main advantages

perfect and uniform ripening in every box and every pallet
minimum weight loss
no manual box handling
energy efficient operation
consumption reduced for partial load
PC ripening operation allowed from home or remote connection
alarm forwarding by e-mail and SMS
immediate refrigerant migration just by software setting
heavy-duty equipment and 3-year exw guarantee
ISO 9001 quality system
banana ripening leadership since 1965

Differences with similar ripening systems

Banana ripening rooms are often built using technologies bought from several vendors, then sold by a third company acting as a contractor or as an engineering. For instance, the electronic controller can be from a vendor, the curtain and the shelving from another vendor, the engineering and the installation by a local (domestic) company, as integrator of different technologies.

The local company usually has little knowledge of component details, while vendors have no information at all about how their technology is being used.

Micheletti Impianti, instead, has developed every component from scratch, thanks to banana ripening experience lasting since 1965. The electronic controller named MI 1000 and the underlying software have been developed just to serve banana ripening rooms as built by Micheletti Impianti. For this reason, the final result is a perfectly integrated ripening room, with commands put on single slave panel, as to control not just ripening functions, but also refrigeration, depression, door, light, and curtain. Following is an example of software integration and features usually not found in common ripening rooms:

integrated drive of a dedicated VFD (inverter) for each depression fan via Modbus
integrated CO₂ probe to drive air renewal
integrated ethylene probe to drive ethylene injections
multiple ethylene injections in synchrony with air renewal, to get a more stable ethylene concentration and to perform ripening and degreening of every fruit
dedicated humidity set point during ripening
dedicated humidity set point during storage
ReFreeX operation (read more about ReFreeX later)
dynamic variation of the evaporating temperature at the central refrigerating unit, according to ripening room needing
number of depression fans during ripening
number of depression fans during storage
door opening enabling or disabling from the slave panel
enabling of door flashing light in case of room alarm
delayed door opening
disabling of cooling, depression, and every other ripening function, by door opening
door locking after ethylene injection and before first air renewal
lighting activation during door movement
lighting activation by door opening, and delayed deactivation after door closure
curtain operation enabling or disabling from the slave panel
curtain operation disabling when door is not completely open

The full list of software features may be found here.

The software keeps tracks analytically of all ripening parameters at every instant. The software is even able to provide Excel quality reports, resuming following synthetic indicators, for each ripening:

ripening serial number
ripening duration
initial product quality
final product quality
ripening process quality
ripening process consumption

The art of ripening is about balancing quality, speed, and energy saving. The software is able to drive the system, as to get the desired trade-off between quality and energy saving, by regulating the depression fans, by on-off or by inverter.

Every control is performed by a master electronic controller, located inside the room electrical board. The controller can be programmed by the local slave panel, located near the room door; by a local PC, usually located in the ripener's office; and by a remote PC, connected to the local PC via Windows Remote Desktop, VNC, or TeamViewer. Remote control is also allowed by Android phone, tablet, and iPhone.

In case of fault of PC or local slave panel, the master controller continues to operate correctly, without any ripening interruption. Moreover, the master controller is not worn by contact with operator hands.

In case of power fault, the master controller resumes the operation at power-up, without any data loss.

The ripening system is perfectly integrated with the revolutionary ReFreeX technology, which have 80% refrigerant reduction and several other advantages detailed in the specific literature.

On 9 June 2014 entered into force the new EU regulation nr. 517/2014, concerning restrictions to refrigerant gas usage. In particular, from 1 January 2020, it will be prohibited to recharge even a single gram of virgin R404A or R507 on refrigerating systems with an overall charge of 11 kg or more. For that reason, the ReFreeX technology is extremely relevant.

Naming convention: rooftop/Chiquita v. curtain/Del Monte

Ripening rooms are sometimes classified accordingly to the depression method.

Our method of using a corridor, a covering curtain, and a depression box can be called curtain method. A competing method using roof top evaporator along all of the room length is called rooftop method.

Originally, the curtain method was also known as Del Monte, while rooftop was also known as Chiquita. However curtain and rooftop are more appropriate names, because Chiquita and Del Monte companies are not necessarily committed to the method named after them.

Pallet format and preparation

The banana ripening system of Micheletti Impianti adapts itself to the pallet shape to ensure perfect ripening for every format.

The standard pallet is as follows.

size (including wood): m 1.23 x 1.05 x 2.15–2.40 h
box stack: 6 x 8–9 (48–54 boxes)
box weight: 18–20 Kg

For pallet height between 1.90 m and 2.40 m, it is possible to reach optimal results by the standard system arrangement. The pallet length and width are not critical for one-level rooms.

Different pallet height and extreme formats are available on request.

For perforated box bags, no pallet preparation is required. For closed bags, it is necessary to extract a small piece of the bag from the box accessible window, and to cut a hole in it. At the end, each box bag will have just one hole, on the outer side of the pallet.

Room loading

The ripener loads the one-level room by a small forklift, better with side shifter. The pallets have to be lined to the two sidewalks at the room sides, as to create two pallet rows that divide two side corridors from a central one.

After loading, the ripener puts three banana probes inside the banana pulp, or better between the bananas, and covers the pallets using the curtain and the electric roller.

An expert ripener can prepare 24 pallets with closed bag, and load the room in about one hour.

Now the room is ready and the computerised system takes care of the ripening process.

What more to turn the key

Starting from our supply, following items are needed to complete the job:

labour for fitting
alloy to braze the refrigeration line piping
lighting
electric wiring materials
connection of the electrical power supply to following boards:

one electrical board for each ripening room
the electrical board of the central unit

water drain from each room evaporator
two or three concrete sidewalks for each room
a PC with Windows 7, or later, to be located in the ripener's office
network connection between the PC office and the nearest banana ripening room

Supply repeated for each room

Room electrical board

The room electrical board is located near the door, on the room front, and contains following components:

master switch
circuit breakers
two SMD electronic boards, named masters, for the computerised control system
two door contactors
one circuit breaker for each depression fan inverter

Computerised control system

For each room there is a stand alone system with microprocessor control, master board, located inside the room electrical board. The microprocessor controls every phase of ripening. The system can be programmed by the slave keyboard-display module, by the office PC, or from a remote location, connected to the office PC via Windows Remote Desktop, VNC, or TeamViewer.

In case of fault of PC or local slave panel, the master board continues to operate correctly, hence the control is highly reliable.

The control system is made by following components:

main master controller, located inside the room electrical board, managing following functions:

cooling
heating
humidification
ethylene injection
air renewal
evaporator fans
depression inverter driving via Modbus

auxiliary master controller, located inside the room electrical board, managing following functions:

door opening, closure, and flashing light
curtain rolling and unrolling
room lighting

slave module, with keyboard and display, located near the room door, with following features:

six-button keyboard performing following functions:

light switching
door opening, closure, and stop
curtain rolling, unrolling, and stop
full programming through a three-level branched menu
shortcut for temperature set point
shortcut for ripening–storage switching
shortcut for forced air renewal
shortcut for forced ethylene injection

display with three-digits and minus sign, showing following parameters:

temperature
humidity
alarms
door operation
curtain operation

seven LEDs, with high efficiency and yellow colour, indicating following functions:

cooling
depression
humidification
air renewal
heating
ethylene
lighting

The control system receives every relevant information by following probes and signals:

three NTC probes for banana temperature, located inside banana boxes near the depression box; the ripener is free to decide which box to control, and can put the probes into the banana pulp or simply between bananas; the latter is advised
one NTC probe for air, located near the door, inside the room
optionally, up to five additional NTC probes, for temperature of bananas and air
humidity probe located near the door, inside the room
ethylene probe located near the door, inside the room
CO₂ probe located near the door, inside the room
optional pressure probe, for the LP side of the refrigerating circuit
NTC probe, for suction pipe temperature, to regulate refrigerant overheating
limit switches for door opening and closure

Following features are supported:

control of depression fan inverters to optimize the balance between banana quality and energy saving
control of room storage temperature by cooling and heating with neutral zone
temperature safety cutoff of cooling and heating
control of room storage humidity by humidification
room air renewal by timer or by CO₂ concentration
optional defrost cycles during storage
scheduled ripening start
five levels of room temperature during ripening, with durations freely programmable from 1 second up to 99 days
control of room ripening humidity by humidification
control of ripening ethylene concentration by ethylene probe
delay of first ethylene injection by timer and by minimum temperature
duration of first ethylene injection
duration of further ethylene injections, period and number
delay of first air renewal
air renewal duration, period and number
duration of forced air renewal
system pause in case of door opening
lighting on in case of door opening
switch-off delay of lighting
curtain operation
refrigerant overheating control, performing as electronic expansion valve
room temperature alarm

Door

The door allows easy operation for room loading, unloading and checking. The door slides vertically inside the room, leaving a clearance of m 2.70 x 2.60 h, for one-level load, and of m 3.0 x 4.95 h, for two-level load.

The door is built by horizontal panels, of 40 mm thickness, with stainless steel hinges and rubber gaskets, and has following accessories:

two oval windows
electric opening with three-phase motor
contactors for opening and closure, drived by the master board
external buttons to open, close, and stop the door, integrated on slave panel
internal push button to open the door
door lock by software, after the ethylene injection and before the first air renewal
door flashing light
photoelectric cells and other safety devices
unlocking handle, to use in case of power fault

Depression system

The depression system forces air to flow from the outer side to the inner side of the pallet, to get a uniform ripening in each box.

The depression system includes following items:

depression box
high pressure fans
one generously oversized VFD (inverter) for each fan
PVC curtain
electric roller
horizontal sliding frame supporting the electric roller
external buttons to roll, unroll, and stop the curtain, integrated on slave panel
internal push button to start curtain unrolling, located near the depression box
air inlet compensation valve
air outlet compensation valve

Ethylene injection system

The ethylene injection triggers the banana ripening. The system manages the injection of the inert blend made by nitrogen and ethylene. The inert blend is absolutely and intrinsically safe because it is impossible to reach the ethylene burst concentration.

The computerised system manages the injections. It is possible to schedule a first injection and further periodic injections, to hold a stable ethylene concentration.The standard injection time for a 24 pallet room is about 50 minutes, the consumption is about 1000 litres; each ethylene cylinder (not provided) contains about 9000 litres.

The system includes following items:

branched line made by copper pipe
shut-off valve
injecting solenoid valve
ethylene probe already mentioned above
driving relay integrated with the computerised ripening control
keyboard shortcut for forced ethylene injection, integrated on the slave panels

Air renewal system

The air renewal provides oxygen and removes excess ethylene and CO₂, to ensure optimal ripening.

The computerised system manages the air renewal. It is possible to schedule periodic air renewal during the ripening cycle or during storage as well. It is even possible to drive air renewal by the CO₂ concentration.

The system includes following items:

air inlet valve, the same used for air inlet compensation
air outlet valve, the same used for air outlet compensation
injecting fan
CO₂ probe already mentioned above
driving relay integrated with the computerised ripening control
keyboard shortcut for forced air renewal, integrated on the slave panels

Room heating system

The heating is needed mostly during the initial phase of the ripening, to increase the banana temperature, before injecting the ethylene.

The heating capacity is calculated to rise the temperature at a rate of about 0.5 °C per hour. Heating is performed by hot gas provided by the central unit or by the stand alone refrigerating unit.

The heating system includes following items:

hot gas solenoid
shut-off valve
mechanical filter

As an option we can provide heating elements with stainless steel sheath. The stainless steel sheath of the elements and the vulcanisation of the endings ensure long lifetime and reduced overheating.

The system by heating elements includes following items:

set of heating elements with stainless steel sheath
safety thermostat
galvanized frame

Room refrigerating system—direct expansion option

The refrigeration is needed mostly after the ripening, to bring back the banana temperature to the storage condition.

The refrigerating capacity is guaranteed to lower the temperature at a rate of at least 0.5 °C per hour, or quicker. The thermostatic valve function is performed pulsing the solenoid valve by the computerised control, that way the system is able to manage all the common refrigerants, as R22, R134a, R404A, R407A, R407C, R407F, R410A, R448A, R449A, R455A, and R507A. The system is able to migrate effortlessly from old refrigerants, as R22, to new refrigerants, as R404A, just by changing a software parameter inside the menu.

The room refrigerating system includes following items:

LU-VE Contardo evaporator, Eurovent certified
solenoid valve, Danfoss brand
shut-off valves
solenoid valve, performing the thermostatic valve function, pulsing on and off under the microprocessor control

Room refrigerating system—water and glycol option

The refrigeration is needed mostly after the ripening, to bring back the banana temperature to the storage condition.

The refrigerating capacity is guaranteed to lower the temperature at a rate of at least 0.5 °C per hour, or quicker. Refrigeration is performed by refrigerant fluid made by water and 20% glycol. The fluid is refrigerated by an outer water chiller not described in this document. The rooms require about 200 litres, per pallet and per hour, of fluid entering at −4 °C; different flows and inlet temperatures are available on request.

The room is provided with connections, left over the ceiling, for fluid inlet and outlet. The room refrigeration system includes following items:

LU-VE Contardo evaporator, Eurovent certified
three-way regulating valve
shut-off valves for fluid inlet and outlet

Consumption comparison among direct expansion and water option

We claim that the direct expansion yields energy saving over water and glycol circulation.

The −4 °C fluid of the water option is refrigerated by a chiller with −10 °C evaporation, while in the direct expansion the evaporation is around 0 °C. For each degree raised in the evaporation, there is a 3 % energy saving, in particular COP at −10/+45 °C is about 2.02, while COP at 0/+45 °C is about 2.70. Assuming a refrigeration load of about 2000 kWh per year per pallet, just for keeping depression and maintaining temperature, the energy requirement for the compressors is 741 kWh/year/pallet, with direct expansion, and 990 kWh/year/pallet, with water and glycol. Hence with water and glycol there is a consumption increase around 249 kWh/year/pallet. In a concrete example of a 24 pallet room, 0.15 EUR/kWh, and 15 years of operations, the energy cost is increased by 249*24*0.15*15=13446 euros per room.

It should be mentioned that the water chillers require a circulation pump, which consumes about 5 % of refrigerating capacity, but this term has been compensated with the inefficiencies of the direct expansion regulation, to get a fair comparison between direct expansion and water.

Branched refrigeration circuit

For rooms connected to a common refrigerating unit (a central unit), the branched circuit is needed to connect the room evaporator to the main refrigeration circuit, placed over the room ceiling.

For stand alone rooms, connected to a dedicated refrigeration unit, the branched circuit is needed to connect the room evaporator to the nearby unit.

The circuit length is 5 meters and includes following items:

liquid line, hot gas line, and suction line, by copper pipe
joints, bends, and elbows
pipe clamps and galvanized channels
elastomeric pipe insulation, CFC and HCFC free

Humidification

The room humidity is constantly monitored on the slave and on the local PC, reading a probe located near the door. Room humidity is an important tool to guess about the banana ripening progress, after the ethylene injection and before the first air renewal; during this time, lasting usually 24 hours, door opening is not allowed; hence it is impossible to touch and smell bananas, to ensure that ripening is in progress. A humidity rise on the slave display is a clear indication of ripening start.

Depression ripening on pallet, as opposed to box by box ripening, usually does not need humidification, because the weight loss on pallet is minimal. However higher humidity improves ethylene absorption by the bananas. For this reason a simple humidification system is provided as follows.

The water drain piping from the evaporator has a branched line leading inside the depression box. A water solenoid valve is kept open when the humidity is under the set point, bringing evaporator drain water to the depression box floor. The depression fans help water evaporation from the floor. This system is cheap, energy efficient and simple to maintain.

The humidification includes following items:

water solenoid valve
shut-off valve
water filter
5 m of copper drain line
T-junction to connect water drain to the drain line going outside the room (the outside line is not provided)

Option for a dedicated compressor for each room

A group of several rooms is better served by a central refrigeration unit, due to non contemporaneous refrigeration load of the rooms. One, two, or even three rooms are instead well served by a dedicated compressor for each room, as described in this paragraph.

Following components are repeated for each room and replace the components from central refrigeration unit to oil and refrigerant charge, in case of dedicated compressor:

Frascold semi-hermetic compressor
crankcase oil heating
safety pressure limiter
shut-off valve
vibration isolator for the discharge line
vibration isolator for the suction line
low pressure probe
high pressure probe
oil pressure probe (for models with oil pump)
filter dryer for the refrigerant liquid line
LU-VE Contardo condenser, Eurovent certified
electrical board, driving the compressor and the condenser by pump-down logic
master electronic controller
slave electronic controller
10 m of suction line by copper pipe (in addition to 5 m on the room side)
10 m of room liquid line by copper pipe (in addition to 5 m on the room side)
10 m of hot gas line by copper pipe
15 m of discharge line by copper pipe
15 m of condenser liquid line by copper pipe
joints, bends, and elbows
pipe clamps and galvanized channels
elastomeric pipe insulation, CFC and HCFC free

Supply common to all the rooms

PC software for ripening and monitor

The microprocessor systems of every banana ripening room and of the refrigeration central unit are connected together on a common RS-485 network. The end of the network is linked to a signal converter from RS-485 to RS-232, to be connected to the COM1 serial port of a PC. All the rooms and the central unit can be programmed and monitored by a software resident on a PC located near to the rooms or in the ripener’s office. Micheletti Impianti provides the software, the interface and the network connection up to the room proximity. The eventual network link from the room proximity to the ripener's office is not provided, and can be realised by an AWG-24 cable with two wires, twisted and shielded. The maximum network length is 1000 meters.

The PC minimum requirement is Windows 7, or later, with a free COM-1 port, native or via USB. An internet connection is required for remote assistance. The PC software allows to manage all banana ripening parameters and the central unit as well. In case of alarm, the software sends one or more e-mails. To manage or monitor the ripening from a remote location, it may be used the Windows Remote Desktop, VNC, or TeamViewer.

Following eatures are supported on PC software:

custom monitor of selected parameters, among all of instrument parameters, as temperatures, pressures, alarm, etc.
modification of any parameter
periodic registration of all parameters
periodic plot print of selected rooms and selected parameters
alarm management by modifiable batch file, for multiple e-mail sending or any other action
export to Excel of raw data and quality data, eventually using a custom Excel template

Central refrigeration unit

The central unit provides the refrigerating capacity and is the most critical component, because its correct working is essential for all the rooms. That is why our central unit is the state of the art, for reliability and simplicity, to ensure smooth and continuous running all over the years, and to perform in an energy efficient way. The central unit should be placed in a dedicated room kept between +20 °C and +40 °C.

The unit is fully assembled and includes following items:

Frascold semi-hermetic compressors, each one with following items:

crankcase oil heating
oil pressure probe (for models with oil pump)
safety pressure limiter (PSH), type approved, as per EN 378-2
pressure cut out (PZH), type approved, as per EN 378-2, for displacement greater than or equal to 25 dm³/s
oil separator (smaller compressors share a common separator)
discharge line check valves, Danfoss brand
vibration isolator for the discharge line
vibration isolator for the suction line

steel suction manifold performing as liquid trap and oil equalizer
steel discharge manifold
two pressure relief valves, with changeover valve, as per EN 378-2, for compressor displacement greater than or equal to 25 dm³/s
low pressure probe
high pressure probe
temperature probe for discharge manifold
temperature probe for suction manifold
filter dryer for refrigerant liquid line, with interchangeable solid cores
shut-off valve for the liquid line
sight glass for the liquid line
pressure service connections

Remote condenser and connecting circuit

The remote condenser should be placed in an open space near the central unit. When possible it should be protected from rain and direct sunshine, to reduce consumption and increase lifetime.

Micheletti Impianti provides following items:

LU-VE Contardo condenser, Eurovent certified
15 m of discharge line by copper pipe
15 m of condenser liquid line by copper pipe
joints, bends, and elbows
pipe clamps and galvanized channels

Electrical board of central unit

The electrical board of the central unit is the second most critical component after the unit itself. To improve serviceability and reduce faults, Micheletti Impianti employs a custom microprocessor controller. Moreover the compressor contactors are generously oversized by 40 %, to increase safe lifetime.

The board includes following items:

master switch
circuit breakers
compressor switches, 40 % oversized

The microprocessor controller, inserted into the board, has following features:

SMD technology
microprocessor with 64 KiB flash memory
EEPROM with 2 KiB
real time clock
phase monitor
primary RS-485 I/O for PC communication
secondary RS-485 I/O for local slave communication
nearby slave instrument, with keyboard and display
triac for condenser speed regulation
low pressure regulation, with dead band and differential
dynamic variation of evaporation temperature, according to ripening room needing
discharge pressure limit, forcing the compressor unload
pressure safety stop for high and low pressures, with independent differentials
oil pressure stop, with independent differentials for each compressor
three relays for condenser fans, with independent set points and differentials
dynamic variation of condensation temperature, according to ripening room needing

Refrigeration main circuit

The main circuit starts from the central refrigerating unit, reaches the nearest room ceiling, and runs over each room ceiling, to connect to the branched circuits. The circuit length provided by Micheletti Impianti is sufficient for 30 m piping from the nearest room ceiling.

The circuit includes following items:

copper pipe for the main suction line
copper pipe for the main liquid line
copper pipe for the main hot-gas line
joints, bends, and elbows
pipe clamps and galvanized channels
elastomeric pipe insulation, CFC and HCFC free

Oil and refrigerant charge

Micheletti Impianti provides oil and refrigerant charge to operate correctly all the rooms. The standard refrigerating gas is R404A, CFC and HCFC free. R134a and other refrigerants are available on request.

Ethylene main circuit

The ethylene main circuit serves the ethylene injection system of each room. The ethylene cylinders should be located close to the first or the last room in the row. The line starts from the cylinders and runs over each room ceiling. The line is suitable for inert blend in factory filled cylinders, to avoid explosion risk.