Abstract
The LPEV principle (Liquid Pump Expansion Valve) of liquid feed control of evaporators in display cabinets is investigated. Using this principle, it is possible to run the evaporator in flooded operation with a low refrigerant charge and high overall heat transfer coefficient. Three types of test models are designed and tested on a display cabinet evaporator, mounted in a vertical test channel. The tests show an improvement in overall heat transfer coefficient of 30 to 70% compared to an evaporator operated with a superheat of 4 to 8 K. The tests are performed with an evaporator capacity up to 5 kW. The size of the LPEV is found to be a diameter of 50 mm and a height of 400 mm. A transient computer lump parameter model of evaporator and LPEV (divided into 4 and 2 tanks respectively). Comparison between measurements and simulations shows good agreement in amplitudes and in some cases poor agreement in the transients of the pressures in evaporator and LPEV. Two approaches of control variables were investigated - a transient temperature signal and a filling time signal. Tests showed that the temperature signal is not suitable as the controlled variable, but the filling time signal is,
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Elefsen, F
[1]
- Danfoss A/S (Denmark)
Citation Formats
Elefsen, F.
Integral control of display cabinet refrigeration systems. Liquid feed control of evaporators.
Denmark: N. p.,
1993.
Web.
Elefsen, F.
Integral control of display cabinet refrigeration systems. Liquid feed control of evaporators.
Denmark.
Elefsen, F.
1993.
"Integral control of display cabinet refrigeration systems. Liquid feed control of evaporators."
Denmark.
@misc{etde_10128476,
title = {Integral control of display cabinet refrigeration systems. Liquid feed control of evaporators}
author = {Elefsen, F}
abstractNote = {The LPEV principle (Liquid Pump Expansion Valve) of liquid feed control of evaporators in display cabinets is investigated. Using this principle, it is possible to run the evaporator in flooded operation with a low refrigerant charge and high overall heat transfer coefficient. Three types of test models are designed and tested on a display cabinet evaporator, mounted in a vertical test channel. The tests show an improvement in overall heat transfer coefficient of 30 to 70% compared to an evaporator operated with a superheat of 4 to 8 K. The tests are performed with an evaporator capacity up to 5 kW. The size of the LPEV is found to be a diameter of 50 mm and a height of 400 mm. A transient computer lump parameter model of evaporator and LPEV (divided into 4 and 2 tanks respectively). Comparison between measurements and simulations shows good agreement in amplitudes and in some cases poor agreement in the transients of the pressures in evaporator and LPEV. Two approaches of control variables were investigated - a transient temperature signal and a filling time signal. Tests showed that the temperature signal is not suitable as the controlled variable, but the filling time signal is, and it is Easy to detect. A digital PI controller was investigated as controller of the evaporator LPEV system. The controller is appropriate in a wide range of evaporator capacities and at start-up conditions. It is concluded that the LPEV principle is an efficient way of controlling liquid feed into evaporators in display cabinets. (AB) (54 refs.)}
place = {Denmark}
year = {1993}
month = {Feb}
}
title = {Integral control of display cabinet refrigeration systems. Liquid feed control of evaporators}
author = {Elefsen, F}
abstractNote = {The LPEV principle (Liquid Pump Expansion Valve) of liquid feed control of evaporators in display cabinets is investigated. Using this principle, it is possible to run the evaporator in flooded operation with a low refrigerant charge and high overall heat transfer coefficient. Three types of test models are designed and tested on a display cabinet evaporator, mounted in a vertical test channel. The tests show an improvement in overall heat transfer coefficient of 30 to 70% compared to an evaporator operated with a superheat of 4 to 8 K. The tests are performed with an evaporator capacity up to 5 kW. The size of the LPEV is found to be a diameter of 50 mm and a height of 400 mm. A transient computer lump parameter model of evaporator and LPEV (divided into 4 and 2 tanks respectively). Comparison between measurements and simulations shows good agreement in amplitudes and in some cases poor agreement in the transients of the pressures in evaporator and LPEV. Two approaches of control variables were investigated - a transient temperature signal and a filling time signal. Tests showed that the temperature signal is not suitable as the controlled variable, but the filling time signal is, and it is Easy to detect. A digital PI controller was investigated as controller of the evaporator LPEV system. The controller is appropriate in a wide range of evaporator capacities and at start-up conditions. It is concluded that the LPEV principle is an efficient way of controlling liquid feed into evaporators in display cabinets. (AB) (54 refs.)}
place = {Denmark}
year = {1993}
month = {Feb}
}