This article presents the technical characteristics and peculiarities description of Bitzer 4NE-20.F4Y-40S compressor being a part of ground-to-air heat pump (operation principle and application features of this type have been described in previous articles of the series about the equipment given).
Bitzer semi-hermetic reciprocating compressors of ECOLINE series are optimized special for R134a. Refrigerant R134a has very advantageous characteristics, especially for mean temperatures and heat pumps.
Bitzer Ecoline Varispeed compressor is equipped with a built-in frequency converter (inverter), thereby offering a possibility smoothly to adjust the performance.
Owing to the frequency converter use, the compressor cooling capacity can be increased by 70% as compared with a fixed frequency of 50 Hz.
A smooth adjustment of the performance enables to minimize the suction pressure oscillations and also the compressor startup rate, and, consequently, to achieve a saving in electricity costs.
The compressor operating time is optimized due to a change of the shaft speed, as well as smooth starts. It leads to the compressor reliability growth.
The high economic feasibility is reached due to a high-efficient operation of the whole system: reduced suction pressure oscillations and optimized operating time of the compressor.
When starting up, the compressor consumes a low starting current .
By virtue of the inverter use a soft adaptation to the required performance and a high seasonal efficiency are achieved by means of the adjustment following the demands.
The drive and valve plates construction is designed for high speeds (for 4-cylinder compressors: 25-87 Hz, as specified in fig. 4.3).
The following diagram, as an example, shows a wide application range of Bitzer 4NE-20.F4Y-40S compressor on R134a at t0 = -10°С, comparing with the compressor cooling capacity at 50 Hz.
Table 4.2 The compressor technical characteristics
|Parameter name||Value||Measurement units|
|Compressor technical characteristics in operating mode|
|Subcooling (after condenser)||0||K|
|Vapour suction temperature||20.00||°C|
|Electric power supply||400V-3-50Hz|
|Power supply voltage||380-420||V|
|Mass flow rate||1088||kg/h|
|Minimum cooling capacity (at 25 Hz)||8.58||kW|
|Maximum cooling capacity (at 87 Hz)||30.6||kW|
|Discharge temperature without cooling||113.9||°C|
|Compressor nominal technical data|
|Volumetric capacity (1450 rev/min 50Hz)||56.25||m3/h|
|Volumetric capacity at 87 Hz||99.2||m3/h|
|Number of cylinders х Diameter х Piston stroke||4 х 70 mm x 42 mm||-|
|Maximum excess pressure (LP/HP)||19/32||bar|
|Suction line connection||42 mm – 1 5/8″||-|
|Discharge line connection||28 mm – 1 1/8″|
|Oil type for:
|BSE32 (As a default)
|Frequency inverter electrical parameters
|Voltage||380..480/3/50 or 60||V/phases/Hz|
|Maximum operating current||55.0||A|
|Maximum consumed power||36.0||kW|
|Motor protection device||SE-B1|
|Anti-vibration dampers||As a default|
|Discharge temperature sensor||+|
|Oil service valve||+|
|Oil heater in crankcase 0..140 W PTC||+|
|Oil pressure monitoring|
Positions in the figure
1 High pressure connection (HP)
2 Installation point for injected gas temperature sensor (HP)
3 Low pressure connection (LP)
4 CIC system: spray nozzle (LP)
5 Fitting for oil fill
6 Oil drain plug
8 Oil return (oil separator)
10 Crankcase heater connection
16 Connection for oil monitoring (oil pressure sensor or differential oil pressure switch “Delta-P”)
21 Connection for service oil valve
Table 4.3 – Reference designations on the graph
|Limits of acceptable application of particular compressors depend on consumed power of frequency inverter|
|_____||M1: Motor 1|
|- – - -||M2: Motor 2|