- Email: [email protected]
Modular floor heating
Industrial n e w s
No uvelles de I'in dustrie Heat pump bureau A heat pump and air conditioning bureau has been launched by the Electricity Council. It aims to advise and provide information for both users and suppliers of heat pumps and air conditioning units. Heat pumps have rapidly grown in popularity as energy prices have risen. Concern has been expressed by both HVCA (Heating and Ventilating Contractors Association) and the Electricity Council that heat pumps should be designed, installed and maintained to high standards. In association with this, a draft standard document to cover safety and performance testing of heat pumps in the UK has been prepared. The Heat Pump and Air Conditioning Bureau, 30 Millbank, London SW1P 4RD, UK
Glycol defrost A glycol deforst system for commercial refrigerated display cabinets has been installed in the UK. The absence of electrical defrosting has reduced the power requirements and removed the need for three-phase electrical supplies to the display cabinets. Glycol pipes are run through the finned evaporators rather than the usual electrical coil heaters. A heat exchanger is interposed between compressors and the condenser, transferring heat to two circuits - one for defrosting and one for space heating. Glycol in the defrost circuit is pumped through an insulated tank, so the temperature of the glycol
Volume 4 Number 5 September 1981
increases. To defrost the cabinet, the glycol is circulated through the finned evaporators in the cabinet. During defrost the cabinet temperature stays almost constant, so there is no partial defrosting of the top layer of products. The defrost is thermostatically ended when the evaporator coils are free of ice but, as a safety back-up, a timeswitch will switch off the defrost system. The other secondary circuit in the heat exchanger contains water, which when heated, serves to heat the sales and storage areas. Fastfreeze Limited, 506 Holderness Road, Hull, North Humberside HU9 3DS, UK
Temperature gauge A differential temperature gauge covering the ranges 0°C to ±100°C and 0°C to ±10°C is available. Startronic say this Model 1 65 can detect changes of ±0.2°C. The input is from thermistors which can be unshrouded, or gas or liquid probes, or surface mounting sensors. When probes are changed, recalibration is unnecessary. Very long leads for the sensors can be used, allowing differential temperature measurement at points which are metres apart. No external power source is required. There is also a preset control which allows measurement of small temperature changes about any point between 0°C and + 100°C. This control is used in the non-differential mode. Startronic Limited, Beeching Road, Bexhill-on-Sea, Sussex TN39 3LG, UK
Model 165 portable differential temperature gauge from Startronic
Altitude/temperature chamber Altitude/temperature chambers have been designed for testing materials in simulated altitude environments up to 200000 ft (60 960 m) and at temperatures from -73°C to +177°C. Each unit of the ZFA-2100 series has an integrated heater and refrigeration system to control temperature. Optional extras include a humidity control for 20--95% humidity; cam-type automatic programmers for temperature or altitude, and a microprocessor programmer for temperature and/or humidity and altitude; and recorders for the three functions. Associated Environmental Systems, 360 Merrimack Street, Lawrence, MA 01842, USA
Modular floor heating Frost heave in cold stores can be prevented by using heating equipment. A modular construction under-floor heating has been developed by Loheat, so if the cold store is dismantled and resited, the same heating system can be relaid. The individual modules are manufactured using ~ in (1.9 cm), 8ft by 4ft (2.44 m by 1.22 m) insulation panels, with stainless
301
steel heating wires embedded at 1 ft (30.5 cm) intervals. Individual panels are enclosed in polythene to keep them dry, and are connected to each other. Loheat Ltd, Hungerford. Berks, UK
Dual compressor A dual compressor centrifugal chiller with a capacity of 450 tons is available. These compressors can be used for air conditioning. While both compressors are operating, they share the load equally at lower power input. One compressor and controls can be isolated for service, while the other continues to function. Individual hermetic motor comparments and motor cooling circuits are designed so that a motor fault will not contaminate the common refrigerant circuit, or interfere with the second compressor's operation. Westinghouse Electric Corporation, Westinghouse Building, Gateway Center, Pittsburgh, Pennsylvania 1 5222, USA
Air conditioning for a coal mine Air conditioning has been installed on the coal-face of a
German coal mine. A refrigerating plant (5860 kW capacity) produces chilled water which, in turn, provides cooling for the air conditioning installations at the coal faces (up to 6 km away). The system is designed to maintain a temperature not exceeding 28°C in the working area. The refrigeration plant is powered by three Stal twin-screw compressors mounted beside the evaporators. Water circulates at 240 m 3 h -~, being cooled from 24 to 3°C. Evaporative condensers placed in the airstream between the downcast and upcast ventilation shafts discharge 7200 kwh of heat away from the mine. The refrigerant used in this installation is Freon 22. Leak detection is with Dytel, from Du Pont. Du Pont de Nemours International S.A., PO Box, CH1211 Geneva 24, Switzerland
Cooling air A device has been designed to cool hot outside air before it reaches the condensing coil of mechanical air conditioning units. The CooI-Pak pre-cooler decreases head pressure and increases the efficiency of the air
The CooI-Pak pre-cooler from Research Products. conditioner. The energy savings and increased efficieny are higher when ambient temperatures are above 85°F (29.5°C). It incorporates a water panel evaporator, with a low resistance to air flow. The housing is made of PVC, built to withstand extreme weather conditions. Research Products Corporation, 1015 E. Washington Avenue, PO Box 1467, Madison, WI 53701, USA
Duplex switching Duplex switching on thermostatic control of refrigeration and freezers will, for example, allow separate sections to be held at different storage temperatures. One section of a cabinet may be used for frozen foods, while the other is storing chilled or fresh foods. Or, when the same storage temperature is needed throughout the cabinet, one section may still require cooling if, for example, it has just been loaded with food. For this multiplex type of installation, variable switching is required. This can be achieved using a Type QR/CB duplex switch, which is a single throw switch making and breaking a circuit on two separate poles simultaneously. Any number can be wired in parallel in a circuit with a single compressor, to achieve the required shut down sequence. Three models are available from
Partial view of the underground air conditioning system for a German coal mine
302
Teddington: the CB94, with remote sensing for -30°C to -5°C; the CB105 with selfcontained sensing for -10°C to +10°C; and the CB106 with
Revue Internationale du Froid
No uvelles de I'in dustrie Heat pump bureau A heat pump and air conditioning bureau has been launched by the Electricity Council. It aims to advise and provide information for both users and suppliers of heat pumps and air conditioning units. Heat pumps have rapidly grown in popularity as energy prices have risen. Concern has been expressed by both HVCA (Heating and Ventilating Contractors Association) and the Electricity Council that heat pumps should be designed, installed and maintained to high standards. In association with this, a draft standard document to cover safety and performance testing of heat pumps in the UK has been prepared. The Heat Pump and Air Conditioning Bureau, 30 Millbank, London SW1P 4RD, UK
Glycol defrost A glycol deforst system for commercial refrigerated display cabinets has been installed in the UK. The absence of electrical defrosting has reduced the power requirements and removed the need for three-phase electrical supplies to the display cabinets. Glycol pipes are run through the finned evaporators rather than the usual electrical coil heaters. A heat exchanger is interposed between compressors and the condenser, transferring heat to two circuits - one for defrosting and one for space heating. Glycol in the defrost circuit is pumped through an insulated tank, so the temperature of the glycol
Volume 4 Number 5 September 1981
increases. To defrost the cabinet, the glycol is circulated through the finned evaporators in the cabinet. During defrost the cabinet temperature stays almost constant, so there is no partial defrosting of the top layer of products. The defrost is thermostatically ended when the evaporator coils are free of ice but, as a safety back-up, a timeswitch will switch off the defrost system. The other secondary circuit in the heat exchanger contains water, which when heated, serves to heat the sales and storage areas. Fastfreeze Limited, 506 Holderness Road, Hull, North Humberside HU9 3DS, UK
Temperature gauge A differential temperature gauge covering the ranges 0°C to ±100°C and 0°C to ±10°C is available. Startronic say this Model 1 65 can detect changes of ±0.2°C. The input is from thermistors which can be unshrouded, or gas or liquid probes, or surface mounting sensors. When probes are changed, recalibration is unnecessary. Very long leads for the sensors can be used, allowing differential temperature measurement at points which are metres apart. No external power source is required. There is also a preset control which allows measurement of small temperature changes about any point between 0°C and + 100°C. This control is used in the non-differential mode. Startronic Limited, Beeching Road, Bexhill-on-Sea, Sussex TN39 3LG, UK
Model 165 portable differential temperature gauge from Startronic
Altitude/temperature chamber Altitude/temperature chambers have been designed for testing materials in simulated altitude environments up to 200000 ft (60 960 m) and at temperatures from -73°C to +177°C. Each unit of the ZFA-2100 series has an integrated heater and refrigeration system to control temperature. Optional extras include a humidity control for 20--95% humidity; cam-type automatic programmers for temperature or altitude, and a microprocessor programmer for temperature and/or humidity and altitude; and recorders for the three functions. Associated Environmental Systems, 360 Merrimack Street, Lawrence, MA 01842, USA
Modular floor heating Frost heave in cold stores can be prevented by using heating equipment. A modular construction under-floor heating has been developed by Loheat, so if the cold store is dismantled and resited, the same heating system can be relaid. The individual modules are manufactured using ~ in (1.9 cm), 8ft by 4ft (2.44 m by 1.22 m) insulation panels, with stainless
301
steel heating wires embedded at 1 ft (30.5 cm) intervals. Individual panels are enclosed in polythene to keep them dry, and are connected to each other. Loheat Ltd, Hungerford. Berks, UK
Dual compressor A dual compressor centrifugal chiller with a capacity of 450 tons is available. These compressors can be used for air conditioning. While both compressors are operating, they share the load equally at lower power input. One compressor and controls can be isolated for service, while the other continues to function. Individual hermetic motor comparments and motor cooling circuits are designed so that a motor fault will not contaminate the common refrigerant circuit, or interfere with the second compressor's operation. Westinghouse Electric Corporation, Westinghouse Building, Gateway Center, Pittsburgh, Pennsylvania 1 5222, USA
Air conditioning for a coal mine Air conditioning has been installed on the coal-face of a
German coal mine. A refrigerating plant (5860 kW capacity) produces chilled water which, in turn, provides cooling for the air conditioning installations at the coal faces (up to 6 km away). The system is designed to maintain a temperature not exceeding 28°C in the working area. The refrigeration plant is powered by three Stal twin-screw compressors mounted beside the evaporators. Water circulates at 240 m 3 h -~, being cooled from 24 to 3°C. Evaporative condensers placed in the airstream between the downcast and upcast ventilation shafts discharge 7200 kwh of heat away from the mine. The refrigerant used in this installation is Freon 22. Leak detection is with Dytel, from Du Pont. Du Pont de Nemours International S.A., PO Box, CH1211 Geneva 24, Switzerland
Cooling air A device has been designed to cool hot outside air before it reaches the condensing coil of mechanical air conditioning units. The CooI-Pak pre-cooler decreases head pressure and increases the efficiency of the air
The CooI-Pak pre-cooler from Research Products. conditioner. The energy savings and increased efficieny are higher when ambient temperatures are above 85°F (29.5°C). It incorporates a water panel evaporator, with a low resistance to air flow. The housing is made of PVC, built to withstand extreme weather conditions. Research Products Corporation, 1015 E. Washington Avenue, PO Box 1467, Madison, WI 53701, USA
Duplex switching Duplex switching on thermostatic control of refrigeration and freezers will, for example, allow separate sections to be held at different storage temperatures. One section of a cabinet may be used for frozen foods, while the other is storing chilled or fresh foods. Or, when the same storage temperature is needed throughout the cabinet, one section may still require cooling if, for example, it has just been loaded with food. For this multiplex type of installation, variable switching is required. This can be achieved using a Type QR/CB duplex switch, which is a single throw switch making and breaking a circuit on two separate poles simultaneously. Any number can be wired in parallel in a circuit with a single compressor, to achieve the required shut down sequence. Three models are available from
Partial view of the underground air conditioning system for a German coal mine
302
Teddington: the CB94, with remote sensing for -30°C to -5°C; the CB105 with selfcontained sensing for -10°C to +10°C; and the CB106 with
Revue Internationale du Froid