7 research outputs found
Virtual sensor of insufficient lubrication in variable speed compressors
The ability to modulate the compressor’s speed and adapt the capacity to the load
has permitted to decrease the annual energy consumption in many applications. However,
in the compressor, having the correct lubrication at high speeds usually imply having insufficient
lubrication at low speeds. This fact has to be considered by manufacturers as it limits
the speed range of the compressor.
In this study, a methodology to establish the working limit of a compressor is proposed. It is
based on the specific consumption surface of the compressor and no oil circulation measurements
are required. A compressor working between 6600 and 900rpm with propane and
POE oil has been used to test the proposed methodology. The results show that lubricating
issues in this compressor start at 1800rpm and rise as speed decreases.The authors would like to acknowledge the Spanish “MINISTERIO DE ECONOMIA Y COMPETITIVIDAD”,
through the project ref- ENE2017-83665-C2-1-P “Maximización de la eficiencia y
minimización del impacto ambiental de bombas de calor para la descarbonización de la calefacción/
acs en los edificios de consumo casi nulo” for the given support. In addition, Ruben
Ossorio would like to thank the Spanish government for his PhD scholarship with reference
PRE2018-083535
Evaluación exergética de un ciclo de autocascada con eyector para aplicaciones de ultrabaja temperatura
El uso de ciclos eyectores en sistemas con R744 ha sido estudiado en los últimos
años mostrando su potencial de mejora, siendo una tecnología implementada a nivel comercial.
Existen otras aplicaciones como los frigoríficos de ultra baja temperatura (ULTR) en los
que, como consecuencia de trabajar a relaciones de presión muy altas, el uso del eyector podría
representar también un potencial de mejora. Hoy en día, con el fin de superar la alta diferencia
de temperatura con costos razonables, se implementan configuraciones conocidas como sistema
de refrigeración en auto cascada.
En este estudio se considera el potencial de mejora del uso de un eyector en el ciclo de autocascada
ULTR. El potencial de mejora se ha analizado mediante el estudio de las irreversibilidades
que se producen en los diferentes elementos del ciclo mediante un enfoque exergético. Además,
se discute el efecto de la temperatura de evaporación sobre el potencial de mejora
Evaluación exergética de un ciclo de autocascada con eyector para aplicaciones de ultrabaja temperatura
El uso de ciclos eyectores en sistemas con R744 ha sido estudiado en los últimos
años mostrando su potencial de mejora, siendo una tecnología implementada a nivel comercial.
Existen otras aplicaciones como los frigoríficos de ultra baja temperatura (ULTR) en los
que, como consecuencia de trabajar a relaciones de presión muy altas, el uso del eyector podría
representar también un potencial de mejora. Hoy en día, con el fin de superar la alta diferencia
de temperatura con costos razonables, se implementan configuraciones conocidas como sistema
de refrigeración en auto cascada.
En este estudio se considera el potencial de mejora del uso de un eyector en el ciclo de autocascada
ULTR. El potencial de mejora se ha analizado mediante el estudio de las irreversibilidades
que se producen en los diferentes elementos del ciclo mediante un enfoque exergético. Además,
se discute el efecto de la temperatura de evaporación sobre el potencial de mejora
Efficiency characterization of a variable speed compressor
[EN] Heat pump systems have been spreading into the heating and air conditioning industry as they offer an
affordable, efficient and reliable solution. They are considered by the EU as the solution to follow in
heating and cooling in order to reach the objectives in reduction of CO2 emissions.
As a consequence of that, there is a growing interest in the development of more efficient heat pump
systems which has motivated the introduction of many technical innovations in the last 10 years. Among
these innovations, the introduction of inverter system has been quite popular. This technology could
imply a significant improvement when the system has to work at non-design conditions. However, in
the standards there is limited information about the characterization procedure of these systems (i.e. EN
13771-1 only refers to fixed speed or vapour injection compressors) and compressor-inverter system are
characterized as a single unit. In that context, it is typical to assume a fixed power loss factor of 3-5%
in the inverter. That power loss factor is considered when designing a new system but could differ in
the final appliance, especially when the system runs at low speed. In conclusion, the knowledge around
variable speed compressors is limited and the system is usually studied as a black box.
In this study, the power of a variable speed compressor and its corresponding inverter have been
measured separately in a calorimeter test bench according the specifications of the norm EN 13771-1.
From these measurements, it has been possible to determine the efficiency of the compressor and the
inverter independently. From these results, the aim of the study is to provide a complete analysis of the
performance of a variable speed compressor system.
The experimental analysis was carried out using the same compressor with two different models of
inverter with the same commutation technology. The study consisted in a battery of tests in which the
same compression conditions were maintained while the rotation speed of the compressor were modified
from 30rps to 120rps.
The results of the paper show that the speed of the compressor and the chosen inverter brand has a high
effect on the efficiency. Moreover, these results can be applied to get the efficiency curve of an inverter
and point out the error that can be made by designers when considering a fixed 3-5% power loss. And
last but not least, the study can also set the bases for other investigations involving the reductionOssorio-Santiago, RJ.; Navarro-Peris, E.; Gonzálvez-Maciá, J.; Albaladejo, P.; López-Navarro, A. (2019). Efficiency characterization of a variable speed compressor. Universidad de Castilla-La Mancha
José Antonio Almendros Ibáñez. 265-275. http://hdl.handle.net/10251/180707S26527
Desarrollo de un sistema de seguridad frente a fugas de gases inflamables para el laboratorio del área térmica del IUIE
[ES] A raíz de la aceptación del protocolo de Montreal, en el cual se prohibieron gran parte de
refrigerantes ampliamente utilizados, se está experimentado con refrigerantes alternativos
entre los cuales destacan hidrocarburos como el propano. Esta memoria describe el diseño de
un sistema de seguridad que detecte concentraciones peligrosas de propano y actúe en
consecuencia activando procedimientos de alarma, ventilación, desactivando fuentes de
ignición y notificando. El sistema se ha implementado en el laboratorio del Instituto Universitario
de Ingeniería Energética (IUIE), funciona como elemento de seguridad para las personas que
trabajan en él y consta de los siguientes elementos, los cuales se detallan en profundidad en
esta memoria:
- Sensores de detección de Propano
- Autómata de lógica programable
- Panel de notificaciones de alarma
- Sistema de ventilación y extracción de gases
- Modulo con conexión Ethernet para notificaciones a distancia[CA] Arran de l’acceptació del protocol de Montreal, al qual es van prohibir gran part dels refrigerants
tradicionals àmpliament emprats, s’està experimentant amb refrigerants alternatius entre els
quals cal destacar hidrocarburs com el propà. Aquesta memòria descriu el disseny de un sistema
de seguretat que detecta concentracions perilloses de propà i actua en conseqüència notificant,
activant procediments d’alarma, ventilació y desactivant fonts d’ignició. El sistema s’ha
implementat al laboratori de l’Institut Universitari d’Ingenieria Energètica (IUIE) i funciona com
a element de seguretat per a les persones que en ell treballen i consta dels següents elements
els quals seran detallats al llarg d’aquest document:
- Sensors de detecció de propà
- Autòmat de lògica programable
- Panell de notificacions d’alarma
- Sistema de ventilació i extracció de gasos
- Mòdul amb connexió Ethernet per a notificar a distància[EN] As a result of the acceptance of the Montreal protocol, in which much of the widely used
refrigerants were banned, systems with alternative refrigerants have been developed. Among
these alternative refrigerants hydrocarbons such as propane stand out.
This report describes the design of a safety system that detects dangerous propane
concentrations and acts accordingly by notifying, activating alarm procedures, ventilation, and
disabling sources of ignition. The system has been implemented in the laboratory of the
Universitary Institute of Energy Engineering (IIE), and works as a safety element for the people
who work in it and consists of the following elements, which are detailed in depth in this report:
- Propane sensors.
- PLC.
- Alarm display front panel.
- Gas extraction system.
- Module with Ethernet connection for remote notifications.TFG
Étude du débit de circulation de l'huile dans un compresseur à spirales à vitesse variable fonctionnant au propane
[EN] The use of hydrocarbons as refrigerants is being more common in recent years. Nevertheless, the solubility of propane in POE oils is significantly higher than in HFCs. This fact has made that POE oils used with hydrocarbons usually have a higher viscosity than the commonly used with HFCs. This approach solves the lubrication problem in the compressor but the way in which oil could affect the system performance is not so widely studied. In this work, an experimental analysis about the oil circulation rate of a variable speed compressor working with propane has been done. The study has analysed the oil circulation at different compressor speeds and evaporating temperatures. The obtained results have shown that the oil circulation rate increases with the compressor speed and reaches values higher than 5% at high speeds. This fact can penalize the COP of the system in more than 15% in these working conditions.The authors would like to acknowledge the Spanish "Ministerio De Economia Y Competitividad", through the project ref-ENE2017-83665-C2-1-P "Maximizacion de la eficiencia y minimizacion del impacto ambiental de bombas de calor para la descarbonizacion de la calefaccion/ACS en los edificios de consumo casi nulo" for the given support. In addition, Ruben Ossorio would like to thanks to the Spanish government his PhD scholarship PRE2018-083535.Ossorio-Santiago, RJ.; Navarro-Peris, E. (2021). Study of oil circulation rate in variable speed scroll compressor working with propane. International Journal of Refrigeration. 123:63-71. https://doi.org/10.1016/j.ijrefrig.2020.12.002637112