In every household, milk is used and stored in a cold place for a day or two. In the same way, the other milk products, i.e. ghee, butter, lassi, paneer, etc. are also needed to store at a lower temperature. The milk and all other dairy products processed or manufactured in a dairy industry needs to be stored at a lower temperature until these are distributed and consumed. Therefore, different types of storage equipment for dairy products are in use depending on the quantity of dairy products to be stored, storage time, storage temperature required, ease in handling the dairy products and any other typical requirements for dairy products. All these are being described as follows:
i. Household Refrigerator
It is very common equipment used in the houses/shops for storage of milk,vegetables, fruits, drinks and other eatables, etc. It is available in various capacities starting from 90 L to 360 L. It is an insulated cabinet in the shape of an almirah.Within this cabinet, a freezer or commonly called icebox is situated at the top.Below this there are 3-4 perforated or grilled shelves. At the bottom, there is a vegetable basket. The door of this refrigerated cabinet is also insulated. Around the icebox generally made of aluminum, the evaporating coils are wrapped. In the backside of cabinet, a hermetic compressor and an air-cooled condenser is fitted.The outlet of condensing coil is joined to the inlet of evaporating coil through acapillary tube crossing the back wall of cabinet.The evaporating coil is dry expansion type. When compressor is started, the refrigerant liquid within the evaporating coil flows and evaporates. While evaporating it absorbs heat and cools the icebox and surrounding air. The cold air around the coil is heavier than the warm air at the bottom. So, by natural convection, the cold air settles down and warm air lifts up.
The circulating cold air current cools all the items placed on shelves. The temperature of cooling coil is low enough such that within the icebox temperature is less than 0 o C. So, the water placed in ice trays convert to ice, which can be used for various purpose in the house. The temperature in the cabinet outside the icebox is generally from 0 o C to 4 o C. Within the cabinet wall a thermostatic control is given which can be adjusted for slow or fast cooling. Due to thermostatic control when the required temperature inside the refrigerator cabinet is achieved, the compressor automatically stops. When this temperature again rises above a certain level, the thermostatic control again starts the compressor. In this way, once the thermostatic control knob is adjusted, the required low temperature is maintained in the refrigerator cabinet.
ii. Deep Freezer
For some type of dairy products or other eatables, e.g., ice-cream, the temperature of the storage space should be very low i.e. below the freezers point, such that,the ice- cream remains in frozen condition. Hence, for storage of ice cream, the generally used household refrigerator will not serve the purpose. For that deep freezers are used. It has a box shape insulated cabinet with an insulated door at the top. The inside wall is made of thin plastic sheet behind which the evaporating coils are fixed all round. As on the outer side of evaporating coil there is an insulating layer, all the cooling effect of coils comes inside the cabinet through the thin sheet. Outside the refrigerated cabinet, there is a hermetic compressor with air fan cooled condensing unit. The length of capillary used is more in case of deep freezer due to which the temperature of evaporating coil is very low generally -20 o C. Deep freezers are generally used at ice-cream shops and parlours.
iii. Walk-in-Cooler
These are big size refrigerating cabinets such that the operator can go inside the cabinet through a door. These are usually installed in large dairies where the quantity of milk products to be stored is large.Walk-in-cooler is generally installed on a platform at a slightly upper level than the floor level. The wall and roof of the cabinet is made of an inner and outer steel sheet. Between these sheets the polyurethane foam is filled. First it is in liquid form and pumped under pressure between the inner and outer wall of sheet metal. As the foam expands it bonds with steel sheets and hardens in place. In this way the wall of cabinet becomes very strong and solid and also light in weight. The wall is fire resistance and waterproof. The foam acts as an insulating material and prevents the heat flow from outside to inside of cabinet. By insulating, the cooling requirement and hence the compressor capacity reduces to a large extent. There is a locking arrangement on the door and it can be opened from both sides. Inside the cabinet, the lights are also provided. The compressor and air-cooled condensing unit are installed in a separate cabinet outside the refrigerated cabinet. The dry expansion type and finned evaporating coil is situated in an enclosed box fitted at one of the wall inside the cooler. In front of the coil a cooling fan is provided. When compressor runs the temperature of evaporating unit falls down. Simultaneously the cooling fan/blower runs which sucks the air flowing over the evaporating coil and circulate this cold are in the whole space of cabinet. In this way inside air gets cooled which further cools the dairy products stored in the cabinet. The open racks may be used for keeping the products in cabinet. At some appropriate point inside the cabinet the probe of a temperature controller is fixed. As the desired temperature reach in the cabinet, temperature controller senses it, and switch off the compressor automatically. The walk in cooler is very easy to use and repair. It may be available in various sizes depending on requirement.
iv. Display Case
It is a highly useful item from business point of view. Most of the food shops,restaurants, ice-cream parlours, sweet shops or any other such type of business place have one or more refrigerated display cases which are made in various sizes and shapes. A display case serves two purposes, one it preserves the foodstuffs until these are sold and other it displays the foodstuffs in an appealing way. A cold air blanket preserves the foods displayed in this type of cases. The compressor and air-cooled condensing unit are generally installed in the bottom of case at a hidden place. The evaporating coil may pass through the shelf or surrounding wall or in the roof depending on various designs. A blower type-evaporating coil may also be used. The food items stored in these cases are usually wrapped in clear and transparent material such as cellophane, which protect them from dust/germ in air.But by wrapping the food the refrigeration load increases considerably than that in case of unwrapped food.
v. Cold Storage
These are actually the small or big size cold rooms made of general construction material i.e. bricks/ cement etc. like any room of a building. Difference is that there is only one entrance door and no window/ ventilation etc. All the inside surface of cold room i.e. walls, roofs, floor, door, etc. are insulated properly. The thickness and amount of kind of insulation depend upon the local conditions. The insulated door is air tight with proper sealing. Inside the cold storage, generally the blower type finned evaporator coil is fixed on any one of the walls. Only the inlet and outlet of evaporator coil crosses the thickness of wall. The evaporator is generally flooded type i.e. full of the refrigerant liquid. A blower sucks the cold air over the coil surface and forces it to flow through the space in cold store. The other components of refrigeration plant, i.e., compressor, condenser, receiver, expansion and control valves are situated outside the cold room and as near as possible to minimize the cost ov. Cold Storagef pipes. The compressors used in a cold storage are generally of reciprocating type and refrigerant used is ammonia. Ammonia is used in cold storage because it is cheap and efficient and also a very good quality refrigerant. The compressed ammonia gas is either condensed in a water-cooled condenser or an evaporative condenser. The condensed ammonia is stored in the receiver from where it is supplied to evaporator through the control valves/ expansion valves. The height of cold room is generally kept low. Cold storage rooms can be made of varying capacity and operating at varying temperature. The storage period is considerably shorter in case the items are stored at a temperature above their freezing point, i.e.,not more than 15 days. However, for items stored at a temperature below their freezing point, storage period can be very large and the cold storage in this case is named as frozen storage. Frozen storage is generally of small size than the cold storage.
i. Household Refrigerator
It is very common equipment used in the houses/shops for storage of milk,vegetables, fruits, drinks and other eatables, etc. It is available in various capacities starting from 90 L to 360 L. It is an insulated cabinet in the shape of an almirah.Within this cabinet, a freezer or commonly called icebox is situated at the top.Below this there are 3-4 perforated or grilled shelves. At the bottom, there is a vegetable basket. The door of this refrigerated cabinet is also insulated. Around the icebox generally made of aluminum, the evaporating coils are wrapped. In the backside of cabinet, a hermetic compressor and an air-cooled condenser is fitted.The outlet of condensing coil is joined to the inlet of evaporating coil through acapillary tube crossing the back wall of cabinet.The evaporating coil is dry expansion type. When compressor is started, the refrigerant liquid within the evaporating coil flows and evaporates. While evaporating it absorbs heat and cools the icebox and surrounding air. The cold air around the coil is heavier than the warm air at the bottom. So, by natural convection, the cold air settles down and warm air lifts up.
The circulating cold air current cools all the items placed on shelves. The temperature of cooling coil is low enough such that within the icebox temperature is less than 0 o C. So, the water placed in ice trays convert to ice, which can be used for various purpose in the house. The temperature in the cabinet outside the icebox is generally from 0 o C to 4 o C. Within the cabinet wall a thermostatic control is given which can be adjusted for slow or fast cooling. Due to thermostatic control when the required temperature inside the refrigerator cabinet is achieved, the compressor automatically stops. When this temperature again rises above a certain level, the thermostatic control again starts the compressor. In this way, once the thermostatic control knob is adjusted, the required low temperature is maintained in the refrigerator cabinet.
ii. Deep Freezer
For some type of dairy products or other eatables, e.g., ice-cream, the temperature of the storage space should be very low i.e. below the freezers point, such that,the ice- cream remains in frozen condition. Hence, for storage of ice cream, the generally used household refrigerator will not serve the purpose. For that deep freezers are used. It has a box shape insulated cabinet with an insulated door at the top. The inside wall is made of thin plastic sheet behind which the evaporating coils are fixed all round. As on the outer side of evaporating coil there is an insulating layer, all the cooling effect of coils comes inside the cabinet through the thin sheet. Outside the refrigerated cabinet, there is a hermetic compressor with air fan cooled condensing unit. The length of capillary used is more in case of deep freezer due to which the temperature of evaporating coil is very low generally -20 o C. Deep freezers are generally used at ice-cream shops and parlours.
iii. Walk-in-Cooler
These are big size refrigerating cabinets such that the operator can go inside the cabinet through a door. These are usually installed in large dairies where the quantity of milk products to be stored is large.Walk-in-cooler is generally installed on a platform at a slightly upper level than the floor level. The wall and roof of the cabinet is made of an inner and outer steel sheet. Between these sheets the polyurethane foam is filled. First it is in liquid form and pumped under pressure between the inner and outer wall of sheet metal. As the foam expands it bonds with steel sheets and hardens in place. In this way the wall of cabinet becomes very strong and solid and also light in weight. The wall is fire resistance and waterproof. The foam acts as an insulating material and prevents the heat flow from outside to inside of cabinet. By insulating, the cooling requirement and hence the compressor capacity reduces to a large extent. There is a locking arrangement on the door and it can be opened from both sides. Inside the cabinet, the lights are also provided. The compressor and air-cooled condensing unit are installed in a separate cabinet outside the refrigerated cabinet. The dry expansion type and finned evaporating coil is situated in an enclosed box fitted at one of the wall inside the cooler. In front of the coil a cooling fan is provided. When compressor runs the temperature of evaporating unit falls down. Simultaneously the cooling fan/blower runs which sucks the air flowing over the evaporating coil and circulate this cold are in the whole space of cabinet. In this way inside air gets cooled which further cools the dairy products stored in the cabinet. The open racks may be used for keeping the products in cabinet. At some appropriate point inside the cabinet the probe of a temperature controller is fixed. As the desired temperature reach in the cabinet, temperature controller senses it, and switch off the compressor automatically. The walk in cooler is very easy to use and repair. It may be available in various sizes depending on requirement.
iv. Display Case
It is a highly useful item from business point of view. Most of the food shops,restaurants, ice-cream parlours, sweet shops or any other such type of business place have one or more refrigerated display cases which are made in various sizes and shapes. A display case serves two purposes, one it preserves the foodstuffs until these are sold and other it displays the foodstuffs in an appealing way. A cold air blanket preserves the foods displayed in this type of cases. The compressor and air-cooled condensing unit are generally installed in the bottom of case at a hidden place. The evaporating coil may pass through the shelf or surrounding wall or in the roof depending on various designs. A blower type-evaporating coil may also be used. The food items stored in these cases are usually wrapped in clear and transparent material such as cellophane, which protect them from dust/germ in air.But by wrapping the food the refrigeration load increases considerably than that in case of unwrapped food.
v. Cold Storage
These are actually the small or big size cold rooms made of general construction material i.e. bricks/ cement etc. like any room of a building. Difference is that there is only one entrance door and no window/ ventilation etc. All the inside surface of cold room i.e. walls, roofs, floor, door, etc. are insulated properly. The thickness and amount of kind of insulation depend upon the local conditions. The insulated door is air tight with proper sealing. Inside the cold storage, generally the blower type finned evaporator coil is fixed on any one of the walls. Only the inlet and outlet of evaporator coil crosses the thickness of wall. The evaporator is generally flooded type i.e. full of the refrigerant liquid. A blower sucks the cold air over the coil surface and forces it to flow through the space in cold store. The other components of refrigeration plant, i.e., compressor, condenser, receiver, expansion and control valves are situated outside the cold room and as near as possible to minimize the cost ov. Cold Storagef pipes. The compressors used in a cold storage are generally of reciprocating type and refrigerant used is ammonia. Ammonia is used in cold storage because it is cheap and efficient and also a very good quality refrigerant. The compressed ammonia gas is either condensed in a water-cooled condenser or an evaporative condenser. The condensed ammonia is stored in the receiver from where it is supplied to evaporator through the control valves/ expansion valves. The height of cold room is generally kept low. Cold storage rooms can be made of varying capacity and operating at varying temperature. The storage period is considerably shorter in case the items are stored at a temperature above their freezing point, i.e.,not more than 15 days. However, for items stored at a temperature below their freezing point, storage period can be very large and the cold storage in this case is named as frozen storage. Frozen storage is generally of small size than the cold storage.
No comments:
Post a Comment
Note: Only a member of this blog may post a comment.