As one of the earliest natural refrigerants, CO2 has a lot of unique advantages, such as zero ODP, negligible GWP, excellent heat transfer coefficient, high volumetric capacity, non-toxicity, non-flammability, and cost effectiveness. Since it was proposed to applying in the mobile air-conditioning, the transcritical CO2 cycle has been attracting great attentions to replace CFC and HCFC refriger...

In this paper, a thermoelectric-assisted vapor compression cycle (TVCC) is proposed for applications in air-source heat pump systems. Compared with the basic vapor compression cycle (BVCC), the TVCC using a thermoelectric heat exchanger (THEX) could enhance the heating capacity of the system in an energy-efficient way. To demonstrate the performance characteristics of TVCC, a case study on this...

Abstract: The performances of thermodynamics cycles are dependent on the properties of refrigerants. The performances of Vuilleumier (VM) cycle heat pump adopting mixture refrigerants are analyzed by MATLAB software using REFPROP programming. At given operating parameters and configuration, performances of the VM cycle adopting pure refrigerant, H2, He or N2 are compared. Thermodynamic properti...

On one hand, the use of solar energy for heating and electricity production should increase in the future to reduce greenhouse emissions. On the other hand, the use of water to water heat pumps allows the production of heat effectively in many applications. In this context, it is appropriate to study the concept of a reversible HP/ORC unit. This innovative system includes a water to water heat ...

this study represents effect of four variables in performance of a heat-pump in two cities of tehran and rasht. a computer program has been developed, simulating a certain heat pump acting in different environments with different refrigerants in heating season. the analysis is based on a homogeneous model. effect of different refrigerants, depth of the buried heat exchangers and moisture conten...

Temperature boosting of waste heat from spacecraft by means of heat pumps makes it possible, under some conditions, to achieve considerable savings in radiator area and mass. This study considers several possibilities for employing workactuated and heat-actuated heat pumps (WAHP and HAHP, respectively) for this purpose. In the former case, the spacecraft power source is required to generate ext...

An 11 kW R410A heat pump system with a two-stage vapor-injected scroll compressor has been developed and tested. A conventional heat pump system with a scroll compressor having the same displacement volume to the vapor-injected scroll compressor has been tested under the same conditions to serve as a baseline. The vaporinjected scroll compressor has been tested with the cycle options of both fl...

A heat pump system requires proper refrigerant charge amount. Once refrigerant is charged into a heat pump system, its charge amount is fixed. For this reason, prediction of optimal refrigerant charge amount is very important in order to yield best performance. Too low charge amount degrades capacity of heat pump. On the other hand, excessive charge amount decreases coefficient of performance (...