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Lc_shi
14-07-2006, 01:54 AM
HI sirs
Who are familaiar with the refrigeration in agriculture field? For example, vegetable from site to supermarket,how about the refrigeration chain through the process?

welcome your input

regards
LC

US Iceman
14-07-2006, 04:43 AM
Hi LC,

This should be an interesting topic. I will start out with some initial cooling types and classifications:

Vacuum cooling
Hydrocooling
Cooling during processing (how many different types are used) - chilled water & air
Cooling for storage (CA, ULO, etc.)
Cooling for distribution (reefers - land & sea)
Supermarkets - display cases, etc.
Consumer - refrigerators/freezersCan anyone elaborate on various experiences and systems they have seen?

Dan
15-07-2006, 03:48 PM
In Florida, precoolers or blast chillers are used for strawberries, tomatoes, and other vegetables. But recently they are washing and packaging them in their end-user plastic containers and palletizing them in the field and then bringing them in for rapid cooling. The precooler is usually a large evaporator and air handler with a wide air return. I have seen 50 hp blower motors. The pallets are lined up double wide and as long as 10 deep. A shroud is placed over the tops and end of the lineup and the cooled air is discharged at high velocity over the lineup while the return air is forced through the plastic packages on the pallets. The goal is to attain a drop from 90 deg F to 40 deg F in an hour. The packaging has made this all but impossible, but it is a gain in overall efficiency from farm to market. I have seen the most primitive systems and clever farmer adaptations to achieve the rapid cooling. The seasons are brief and much of the equipment will be idle 9 months out of the year.

S.K.VARDE
22-07-2006, 03:56 PM
Dear friends

I have my own article on Food preservation which was composed In 1995 and was circulated to many NGOs and at the seminars on Food Preservations in India.

I can submit the brief abstract of the same here.


In any country, except some, about 30 to 40% of the fresh produce are lost on account of inadequate post harvest infrastructure and storage facilities.

If we concentrate on improvement on post harveat infrastructure, like post harvest treatment, grading, storage, transportation and processing facilities of perishable produce in perticular, the reduction in the losses is estimated to be 20% or even more and can save or recover the huge amount of money.

The production can be made available in the market at cheaper price and also the price fluctuation of the seasonal produce can be restricted to a great extent. Besides this the produce can be exported at goog price round the year.

The different variety of fruits & Vegetables grow in different seasons and many of them required and being consumed whole year. The produce of one place may be consumed by the people far away from the grown up place.

The lives of different produce are also different according to their microstructure. As has been revealed that fruits & Vegetables are living organism which undergo with all physiological and pathological processes associated with their life.

Basically three major molecular components i.e. Carbohydrates, Proteins and Fats. These organic chemical compounds provide Vitamins and Minerals required by human beings. The distraction of one of these consequently causes the spoilage of the food.

The spoilage comes in the form of Bad odor, Bad taste, Bad physical appearence, uncommon color, loss of weight, softening, souring, Roting, Wilting od Moulding or in combined form.

When ew talk of food preservation, we mean that the preservation of platibility and nutritive value of the food, preventing the natural spoilage with respect to time.

The food preservation technology has developed sufficiently to preserve the wide variety of fruits & Vegetables and for a considerable long time as near the point of freshness as possible.


Dear friends, I shall continue this topic next days,

thanks

Lc_shi
24-07-2006, 01:39 AM
hi Varde
I'm much interested in your research in Food preservation tech.Would you pls share your articles on this topic?

regards
LC

Dan
24-07-2006, 11:46 PM
Thank you Varde. I look forward to further posts with greater detail.

Samarjit Sen
11-08-2006, 06:05 PM
Recently I undertook a project for pre cooling and storage of grapes as a refrigeration consultant. The refrigeration units were designed and being installed by two very reputable refrigeration firms in our country. Unfortunately the design was wrong. For the Pre Cooling Unit I suggested a model of Guntner Coil with Adiabatic umidifiers for maintaining the RH. The pre cooling chambers are working very efficiently and the concept which was different from the ones that are generally adopted were very much appreciated. For the Cold Store section, the units supplied and installed by another very reputable firm could not perform. The reason being the Coils being defective. It appears that while designing the air circulation was not considered and as such the power consumed has gone up and the plants are ineffective. I feel that specially for the designing of a refrigeration system every details have to be studied and plant designed properly. Post Harvest treatment deserves more attention as they are living and that is the only way to keep the produces healthy and fresh. Every produce has a different storage conditions. For the above project I was consulted at a very late stage after the damage was done but I tried to rescue the project as far as possible.

Lc_shi
12-08-2006, 02:15 AM
Hi Sen
It's very good to share your experience. Hope you can continue to offer some more case:).

regards
LC

Samarjit Sen
12-08-2006, 01:03 PM
Hi LC,
In my experience of 42 years in the field of refrigeration, I have found the best results for agriculture refrigeration is providing refrigeration by a DX system. Since the agricultural produce requires fast removal of field heat say within 6 hrs and the core temperature of the produce should be brought down to 0 Deg C, and at the same time maintaining a RH of 95 to 98 %, it is best to use an Air Cooler Unit with a large face area based on the load calculations, high velocity air and large quantity of supply air. The system should be designed at - 8 Deg C Evaporation with a low Td and the supply air temperature from the coil should be - 2 Deg C. For maintaining the Relative Humidity I would advise that a seperate Adiabatic Humidifier of the capacity as per load calculation should be provided. However it is important that the water moisture size should be between 3 to 5 micron in size. By this there will be no droplets of water on the products.

It is important that every aspect of the system has to be properly designed and proper selection of equipments and coils be used. Further I have noticed that by using semi hermetic compressors, balanced port TEV's ,Crankcase Pressure Regulator Valves and last but not the least a good Coalescent Oil Seperator can not only improve the performance but can also reduce considerably the power consumption.

It is very important that specially for the Post Harvest refrigeration application designing is very impotant. The technology has advanced and more importance has to be given to the efficiency, economics and the power consumption. Refrigeration is completely different from Air Conditioning.

With best wishes,

Samarjit

Josip
13-08-2006, 10:01 AM
Hi,


I have found the best results for agriculture refrigeration is providing refrigeration by a DX system. Since the agricultural produce requires fast removal of field heat say within 6 hrs and the core temperature of the produce should be brought down to 0 Deg C

In my country we have a couple of very old and big CA cold stores, with pumped (cheap) ammonia, humidifiers and CA equipment. Now start installations of some brand new ULO cold stores with smaller room capacity due to delivery requests. When you open one room you must sell that product in some short time;)

Cooling during processing (pumped ammonia/air) I met in chocolate factory (nice and sweet job :) , it is hard to understand how much chocolate we have to eat until we set up equipment ;) )

In Turkey I started up (ref equipment delivered by York 600kW with 35 kg of ammonia PHE evaporator and condenser) one ULO cold store (equipment delivered by one company from Italy) with indirect cooling ammonia/glycol water (three-way valves and circulation pumps on glycol side) all Unisab and PC controlled and working fine.

I will give some more info about one big cold store if we get that job ;)

With other types (from US Iceman list ) I do not have experience)



1. Vacuum cooling
2. Hydrocooling
3. Cooling during processing (how many different types are used) - chilled water & air
4. Cooling for storage (CA, ULO, etc.)
5. Cooling for distribution (reefers - land & sea)
6. Supermarkets - display cases, etc.
7. Consumer - refrigerators/freezers


Best regards, Josip :)

Darshi
09-11-2006, 09:40 AM
Hi
I read a paper recommending use of evaporative cooling for short term vegetable storage .Is it possible
I think it was a horticulture society magazine.
Is it possible to store vegetables for seven days with evaporative cooling?
What is the Temperature and humidity required for short term storage?

Samarjit Sen
09-11-2006, 05:51 PM
For storage of fruits and vegetables temperature and humidity are the basic requirements. For a short time storage of seven days a temperature of 4 Deg. C will be allright. but the humidity has to be maintained a
between 80 to 90 %. For a longer period a temperature of -1 to 0 Deg. C is advisable. It is very important that after the harvesting the products are pre cooled to remove the field heat. This has to be done at a temperature of -1 Deg. C with a RH of 90 to 95%. Air is a very important factor for agricultural produce storage or pre cooling.

With proper pre cooling the quality of the products remain as good as fresh. I have seen grapes after being pre cooled properly and under perfect conditions, remained as good as ever after 90 days stored in a temperature of 0 Deg. C.

Another point which I have noted that the moisture particles for maintaining the humidity should be as low as possible. I use adiabatic humidifiers which generates moisture particles as low as 3 microns. Most of the units has a moisture particles upto 15 microns, which causes water drops on the products which creates chill injury.

I personally would not reccommend evaporative cooling for a short time storage as you will not be able to control the temperature and the humidity.

Handyman-1
17-11-2006, 01:04 AM
For storage of fruits and vegetables temperature and humidity are the basic requirements. For a short time storage of seven days a temperature of 4 Deg. C will be allright. but the humidity has to be maintained a
between 80 to 90 %. For a longer period a temperature of -1 to 0 Deg. C is advisable. It is very important that after the harvesting the products are pre cooled to remove the field heat. This has to be done at a temperature of -1 Deg. C with a RH of 90 to 95%. Air is a very important factor for agricultural produce storage or pre cooling.


The temperature & humidity depends on the particular product:

1) Banana - 56-59 F/90-95% RH
2) Papaya - 45-55 F/85-90% RH
3) Calabaza - 50-55 F/50-70% RH
4) Chayote - 45 F/85-90% RH

Above data are from:
Commercial Cooling of Fruits, Vegetables, & Flowers, Revised Edition
University of California, Agricultural & Natural resources Publication 21567

thoist
30-11-2006, 08:04 AM
Hi Sen,
Your experience about " agriculture..." is very interesting it helps me solve some problems with my refrigeration system. I hope you can give some more cases.
Thanks
regards

Biomass
30-11-2006, 04:49 PM
Hello Refrigerants.
I'm new to this and I have to admit to not being in the trade. I grow raspberries in the UK. But am in the process of installing biomass (wood) boilers for heating my glasshouses. In looking for a use for these boilers in the warmer months I thought of using the heat for ammonia evap. cooling to cool the fruits. Does anyone know if this is possible and could it be designed to include a prestorage rapid cool (airblast) system.
Also what would be the minimum temp achievable using this method.
Thanks and sorry to butt in on a thread, I'm not sure how this works yet.
Biomass

Samarjit Sen
04-01-2007, 05:38 PM
Sorry Thoist,

I have been visiting the forum, but somehow your post missed me. We are doing another project of Grapes Precooling and Cold Storage. We are using Square Panels, puf panels for the chambers. This is company from Thailand. This is their first Cold Storage panel job in India. There products appear to be good and if it works out they way I want it, then they would have a very good market.

Since you are also in the same feild, could you please let me know as to what type of refrigeration system you are using. There are a number of systems as you know, but depending on the application and the fruits and vegetables, we have to select the proper units. I have always preferred Semi Hermetic Compressors with water cooled condensers. This has resulted in better efficiency and lower power consumption.

It would be nive to share the experiences. In case you require any assistance, please do let me know. I am in this field now for over 42 years.

With best wishes,

munesh
01-02-2007, 01:06 PM
Hi Everyone,
Can anyone suggest me a few players in India having a complete cold chain solution.
I mean from harvesting to the consumption.

Even if there are specialised I will prefer to have those details.

Also if you can share with some articles regarding the same will be much appreciated.

Brian_UK
01-02-2007, 11:53 PM
Hello Refrigerants.
I'm new to this and I have to admit to not being in the trade. I grow raspberries in the UK. But am in the process of installing biomass (wood) boilers for heating my glasshouses. In looking for a use for these boilers in the warmer months I thought of using the heat for ammonia evap. cooling to cool the fruits. Does anyone know if this is possible and could it be designed to include a prestorage rapid cool (airblast) system.
Also what would be the minimum temp achievable using this method.
Thanks and sorry to butt in on a thread, I'm not sure how this works yet.
BiomassHi Biomass and welcome to the forum.

I'm sure that someone will have thoughts on your plan however I will ask one to the other moderators to relocate your post to another area where it will get it's own response.