I. INTRODUCTION QCD, the non-abelian gauge theory of strong interaction, predicts a phase transition be- tween a hot and dense hadron gas (HG) and the quark-gluon dominated phase which is called as quark gluon plasma (QGP) [1,2]. However, even after an intensive experimental as well as theoretical research spreading over the last two decades, our knowledge regarding the properties and signals of QGP is still very limited [3,4]. Even the phase boundary between the two phases remains in the literature as a conjectured one because the non-perturbative aspects of QCD are still dominant near the region close to the phase transition. In order to test the appearance of a deconfined QGP which exists in a transient phase, we need a proper understanding of its subsequent hadronization process about which our knowledge is really very poor. The numerical method of lattice QCD can properly describe both the phases i.e., QGP and HG. However, lattice QCD studies have yielded results for finite and large values of temperature T and µ$_{B}$ =0 and now we have surmounted difficulties in getting results for small, non vanishing values of µ$_{B}$ [5,6]. Thus we feel an urgent need to formulate a phenomenological model which can successfully reproduce the lattice QCD data and hence we can further use it to obtain the properties of QGP and to determine the QCD phase diagram in the entire (T, µ$_{B}$ ) plane. In this paper, we present a thermodynamically self-consistent quasiparticle model of QCD which describes a gas of quasiparticles with effective masses generated through the inter- actions among its basic constituents. This model has been found to work well above and around critical temperature T$_{c}$ . In order to describe the low energy HG phase, we work with our own model which has been found to give a proper description of the hot and dense HG [7]. The investigation of the structure of the QCD phase diagram is one of the most important and challenging topics in the nuclear and particle physics today. The precise determination of the phase boundary between QGP and HG at high temperature T and small µ$_{B}$ has been a subject of intense research in recent years from experimental as well as theoretical points of view [8-9]. Lattice simulations first revealed that the transition between HG and QGP phase at µ$_{B}$ =0 and large T is a crossover transition and there were further indications that the crossover transition turned into a first order chiral phase transition for nonvanishing and finite values of µ$_{B}$ [10]. Several attempts have since been made to locate precisely the critical end point (CEP) i.e., an ending point of the first order chiral transition